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Energy2green Wind And Solar Power System Summary

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High Wind Speeds

The strongest surface winds observed by in situ measurements on Mars are believed to be 30 to 50 meters per second (67 to 111 miles per hour) based on eolian deposits at the Viking I landing site. From a terrestrial perspective, these wind speeds appear to represent a significant hazard. However, when the lower atmospheric dynamic pressure on Mars, resulting from a less dense atmosphere than on Earth, is accounted for, the Earth-equivalent wind speeds are much less. Dynamic pressure is proportional to the air density times the square of the wind speed, so that the following comparisons can be made For the same wind speed, the dynamic pressure on Mars is less than on Earth by the ratio of air densities, or a factor of about 82. For the same dynamic pressure, the wind speed on Mars must be greater than on Earth by the square root of this number, or a factor of about 9. Another potential hazard associated with wind is abrasion by windblown particles. Suspended dust is so fine that it is...

Preface to the second edition

Astronomy is not an experimental science like physics it is a natural science like geology or meteorology. We must take the Universe as we find it, and deduce how the basic properties of matter have constrained the galaxies that happened to form. Sometimes our understanding is general but not detailed. We can estimate how much water the Sun's heat can evaporate from Earth's oceans, and indeed this is roughly the amount that falls as rain each day wind speeds are approximately what is required to dissipate the solar power absorbed by the ground and the air. But we cannot predict from physical principles when the wind will blow or the rain fall. Similarly, we know why stellar masses cannot be far larger or smaller than they are, but we cannot predict the relative numbers of stars that are born with each mass. Other obvious regularities, such as the rather tight relations between a galaxy's luminosity and the stellar orbital speeds within it, are not yet properly understood. But we trust...

Summary Of Observations

Have been in situ spacecraft detection and the remote sensing of coronal photons. Some key results of such measurements are summarized below. Other diagnostic techniques that cannot be discussed in detail in this brief review are the scintillation of radio waves passing through the corona (Bastian 2001), the analysis of backscattered solar radiation by interstellar atoms (Bertaux et al. 1996), and using comets as probes of the solar wind energy budget (Raymond et al. 1998).

ADEOS 1, also known by its national name, Midori ( green ), was the first resources satellite to observe the planet in an integrated way. Developed and managed by Japan's NASDA (National Space Development Agency), it carried eight instruments supplied by NASDA, NASA, and CNES (the French space agency) to monitor worldwide environmental changes, including global warming, depletion of the ozone layer, and shrinking of tropical rain forests. Due to structural damage, the satellite went off-line after only nine months in orbit. ADEOS 2, scheduled for launch in November 2002, will continue where its predecessor left off and also study the global circulation of energy and water. Additionally, it will contribute to NASA's EOS (Earth Observing System) by carrying NASA's Seawinds scatterometer, a microwave radar to measure near-surface wind velocity and oceanic cloud conditions, which scientists hope will improve their ability to forecast and model global...

Ionized Comp Neutral Coup

As will be explained in the next section, this unknown quantity is now identified as the southward component (-Bz) of the interplanetary magnetic field (IMF), or more accurately, a specific combination of the solar wind speed V, the IMF magnitude B, and its polar angle 0. The magnetosphere responds to

Structure and Dynamics of the Outer Radiation Belt

Abstract Since the early 1990s a series of spacecraft missions have completely transformed our view of the electron radiation belts. This paper summarizes a number of new results on the structure and dynamics of the belts obtained from those measurements. First, the structure of the outer electron belt is discussed with emphasis on the regions (P0-P2) distinguished on the basis of the time variations of the electron flux. Each region is characterized by distinct set of acceleration and loss processes. While these processes are traditionally represented by diffusion models, new empirical models have emerged in the last decade. These models are developed from the observed dynamics of the flux as a function of L shell and energy. We have developed such models in each Pi region, and introduce methods of writing them as empirical diffusion-convection models. Since any realistic space weather model must be driven by interplanetary activity parameters, we discuss the development of...

Summary And Discussion

Input-output analysis of the fluxes in terms of the preceding solar wind IMF variations shows that geoeffective solar wind inputs are different for each region and at varying degrees the variance in P1 flux is partly explained by changes in the solar wind velocity, VSW. The impulse response H(t L LP1) shows a t 2-3 day delay relative to the arrival of the solar wind. The response occurs for high-speed streams and is particularly well-known for je(L 6.6). The impulse response in P0 peaks more rapidly, at t

Large scale morphology

The magnetic field, the solar wind velocity and the shock normal at the point the magnetic field intersects the shock are not a priori co-planar. Consequently, diagrams of the foreshock that are two dimensional in nature are implicitly simplified. Whilst the upstream boundary of the ion and electron foreshock is

AO System Fundamental Parameters

The relevant parameter for the deformable mirror is the number of degrees of freedom, usually given by the number of actuators. The aim of this device is to introduce in the incoming wavefront an optical path difference equal and opposite to the perturbation induced by the atmosphere at a given time. The sum of the two perturbations will give as a result a plane wave. As mentioned, the spatial scale of the atmospheric perturbation is given by the r0 value. Hence, in order to have the proper resolution on the corrective device, we need to have an actuator grid with pitch smaller then r0. In this case, the total number of actuators can be estimated to be of the order of (D r0)2. The second parameter considered is the time required to compute and apply the correction. As we find in Sect. 3.3, the correlation time of the atmosphere is given in the Taylor hypothesis as t r0 v, where v is the considered wind velocity. To be able to apply an efficient correction, the cycle time of the system...

Different Modes of the Magnetotail Flux Transport

As illustrated in Figure 1 southward IMF BZ drives the convection in the magnetotail, thereby transferring solar wind energy into the magnetosphere. In the magnetotail, evidence supporting the storage (loading) and release (unloading) of energy associated with substorms can be observed as increase and recover of the energy density (total pressure) in the midtail (Caan et al., 1973). The mode of dissipation of the accumulated energy observed in the tail, however, does not seem always the same. That is, it is not a simple enhancement of the energy and then a decrease toward the quiet level. For example, at times the accumulated energy is rapidly dissipated during a substorm, whereas at other times the dissipation can occur more gradually during ongoing magnetic activity (Fairfield etal., 1981). During the latter cases, the energy supplied by the solar wind may even exceed that being dissipated, thus causing the tail energy to increase. On the other hand, there are times when convection...

Solar Wind Density Influences on Substorms

So far we have discussed mainly the effect of the IMF Bz on the magnetotail response which can be ascribed to the process illustrated in Figure 1. The input solar wind energy causes the tail to be stressed (loading) or directly drives night side reconnection (SMC) but then the tail relaxes (unloading) to the initial state at some stage so that solar wind input and output will eventually be balanced. Yet, within a single substorm cycle, the input and output is not always balanced, as clearly shown in recent observations by Sergeev et al. (2005). In this event, the tail was significantly loaded, but the unloading took place in a rather modest fashion, indicating that the amount of dissipation in the tail during a single substorm can not be determined from the amount of the input energy only. Here another solar wind factor, namely the density which determines the precondition of the plasma sheet was suggested to play a significant role in the magnetospheric response.

Hazards from Atmospheric Dynamics

The committee believes that in light of the low dynamic atmospheric pressures experienced on Mars, no further characterization of wind speed on Mars is required prior to the first human mission. The surface winds are sufficiently characterized to allow system designers to ensure human safety on the planet by means of robust designs.

Atmosphere And Weather

Despite the thin air on Mars, weather occurs, and it can be extreme. Winds aloft can reach speeds of around 400 kilometers per hour (250 miles per hour) near the surface, they commonly rise to 120 kilometers per hour (75 miles per hour). It would be a mistake to say that such winds are of hurricane force because the thin air on Mars produces far less wind pressure for a given wind speed than the air on Earth. However, dust particles from the surface are picked up and travel right along with the wind, blowing high up into the atmosphere, where they at times shroud the planet completely. During these massive dust storms, which can be accompanied by lightning, the surface features of the planet practically disappear. As seen from the surface, such a storm would produce a dark red sky, obscuring the sun and casting an evil gloom over the landscape.

Correlation between composition and kinetic parameters

It is readily apparent in Figure 3.7 that there is an anticorrelation between the solar wind speed, va, and the oxygen charge-state temperature, TO. In Figure 3.12 we plot just these parameters in two polar plots much like the ones of SWOOPS (cf. Figure 3.2), whereby the anticorrelation becomes particularly clear. This anticorrelation was studied in some detail in a pair of papers Gloeckler, Zurbuchen, and Geiss (2003) Fisk (2003). During a 166-day time period around the solar minimum in 1996-1997, Gloeckler, Zurbuchen, and Geiss (2003) first determined a correlation V 144 T 88, where V is the solar wind speed in km s and T is the freezing-in temperature from oxygen charge states in MK. The correlation is found to be very tight except at times when an ICME passes by (see Section 3.5.2). On the other hand, Fisk (2003) derives a theoretical relation between coronal electron temperature and terminal solar wind speed squared (i.e., its energy) of the form Figure 3.12. Polar plots of the...

Plutos Euvfuv Vertical Atmospheric Opacity

Ions reach a maximum speed of twice the solar wind velocity, so that ions have a maximum energy of m(2Vsw)2 2 (Bagenal et al. 1997), where m is the mass of the ion and Vsw is the solar wind velocity (approximately 450 kms-1). Thus, N+ will have energies near 35 keV, and N+ will have energies near 70 keV. These are within PEPSSI's energy range, which can measure particles with energies up to 1 MeV. Since the bulk of the pickup ions originate from Pluto, PEPSSI supports the Group 1 objective of measuring the atmospheric escape rate by measuring the number and type of these ions. In addition, the energy range of PEPSSI supports the Group 2 objective of characterizing Pluto's solar wind interaction.

Other Types ofXRay Sources Related to Star Formation

In some cases, enhanced extended background emission was found that is spatially and spectrally different from the point source population, and was interpreted as diffuse emission 51 . Analysis of the associated low signal-to-noise X-ray spectra has not allowed to unambiguously determine the production mechanism for the diffuse component. Its coincidence with the presence of early O stars and the comparatively soft spectrum suggest that it originates from shocks in which the wind energy of the hot stars is thermalized.

CMEDriven Shock Propagation

The two simplest solutions of these equations, assuming spherically symmetric, hydrodynamic flows (B 0), and neglecting gravity, are the blast wave with constant total energy (created, say, by an impulsive enhancement in solar wind speed) and the driven shock with increasing energy content (created, say, by a sudden and persistent increase in wind speed). Under further simplifying assumptions, these two cases may be described by analytical self-similar solutions (Rogers, 1957 Sedov, 1959 Parker, 1961, 1963 Chevalier, 1982). The blast wave is a single forward shock, whereas the driven configuration involves a forward shock propagating into the solar wind ahead and a reverse shock propagating backwards into the ambient wind behind, but swept outwards by the flow. These two simple cases provide a framework for interpreting shock propagation in the corona and solar wind in more general cases. The CME-associated shock is initially driven, since CMEs appear to retain their high speeds for...

Magnetic Storms and the Ionosphere

A crude picture of the magnetic substorm process is given in Figure 2-21. An important factor in the generation of substorm energy is the direction of the Interplanetary Magnetic Field (IMF) along the dipole axis of the earth. When it is directed southward, as shown in Figure 2-20, the plasma sheet becomes pinched driving ionization toward the polar regions. Sheeley et al. 1976 associated high speed solar wind and geomagnetic activity (See Figure 2-11). The current view is that solar wind speed and the IMF direction are fundamental discriminants.

Automated imaging telescopes

Finger Lakes Instrumentation which incorporates a512 x 512 e2v technologies back-illuminated CCD with 24 m pixels. Equally important is the weather station hardware and software which monitors the temperature, relative humidity (RH), and wind speed. A raindrop sensor ensures that there is no precipitation, and an infrared sensor with a 12 m-13 m filter pointing at the sky serves as a cloud monitor. If the RH or wind speed exceed critical values, or if a single drop of rain hits the raindrop sensor, direct circuits from the weather station to the dome shutter motor override all computer control and close the dome shutter. In addition, there is a solar cell which prevents opening when the Sun is above a 10 altitude, and there is a dead-man timer which closes the observatory if no telescope activity occurs for 20 minutes. Highly efficient image-processing software is a major reason for the success of the supernova search program (Filippenko et al., 2001).

Temporal fluctuations 551 The winddriven frozen turbulence hypothesis

The relationship between temporal and spatial fluctuations in the atmosphere can be understood by a simple hypothesis due to G. I. Taylor. We assume that in a frame moving with the local wind velocity the turbulent structure changes very slowly, and what we see as temporal fluctuation is in fact the spatial structure being blown across the field of view. The scaling argument which justifies this assumption, in the spirit of section 5.3.1, goes as follows (Tatarski 1961). The wind velocity normal to the line of sight is vn. For an optical path length L the transverse correlation distance of amplitude fluctuations is XL (section 5.4.1) and thus the correlation time r0 will be, according to the frozen-turbulence hypothesis, r0 s XL vn. Now we recall from section 5.3.1 that the typical lifetime of a fluctuation of scale l is rl l vl l (el)3, where vl was the typical random velocity in a coherent region and e the heat input. For correlation distance l XL, it follows that the time-scale for...

Frequency spectrum of fluctuations

Since we are looking at the component of the movement in the direction of the wind velocity, the Fourier transform needed is one-dimensional. Using (528) to express the structure function and (5.7) to relate this to the autocorrelation function, we have Since the power spectrum scales with wind velocity, it is convenient to define a coherence time t0 in order to normalize values of the power spectrum under different conditions. The coherence time can be defined as the time for phase changes of order n to occur, i.e. D0(t0) nf, but there is no general agreement over the definition. Then t0 is related to Fried's parameter and the wind velocity by t0 0.314r0 vn. It follows that measurements of the power spectrum presented as a function of ft0 should lie on a universal curve. A typical value of t0 is 3 msec (for r0 10 cm and vn 10ms-1).

Automated detection of CMEs

The CELIAS MTOF PM instrument on SOHO measures the solar wind speed, density and temperature. A group at the University of Maryland recently implemented a Shockspotter program to identify interplanetary shocks in near-real time using proton monitor data. The program is based on semi-empirical algorithms using only solar wind proton data (since no magnetometer data is available on SOHO). Shock candidates are classified into 4 distinct zones, with confidence levels ranging from about 40 to 99 . Results have been used to study the frequency distribution of interplanetary shocks over the solar cycle.

Carrington Longitude

Association between the magnetic polarities of polar coronal holes and fast solar wind streams. This figure is one of the earliest to show this relationship. The upper panel contains the solar wind speed over a single solar rotation as a function of solar (Carrington) longitude. The pluses and minuses denote the magnetic field polarity in the two fast streams. Because of the definition of longitude, time proceeds from right to left in the diagram with the speed rising from 300-400 km s to 800 km s. The front edges of the fast streams are to the right and the trailing edges to the left. The lower panel shows the measured coronal brightness as a function of latitude and longitude. The brightness contours outline the tilted coronal disk or streamer belt. The two north and south polar coronal holes extend to the equator at longitudes of 90 and 270 and the observed magnetic polarities are indicated. The figure shows that the fast streams are correlated with the polar coronal...

What Determines the Geoeffectivity of ICMEs

In reconnection theory the reconnection rate is expressed in terms of the reconnection electric field, which in this case is E v Bs, where v is the solar wind speed and Bs the southward component of the IMF. A fast ICME can enhance both factors. The velocities of the shock, the ICME and the post-shock streams can easily be more than twice the background solar wind speed. The IMF in the sheath region between the shock and the ejecta is strongly compressed. If the IMF ahead of a fast ICME already has a southward component, the shock increases it typically by a factor of 3-4. This way the sheath region can drive a storm even if the ICME itself does not hit the magnetosphere. The southward IMF component may be further amplified by draping of the magnetic field around the ICME (Gosling and McComas, 1987), which can lead to a southward IMF component even in cases where the pre-existing IMF is slightly northward. This mechanism works also when the ICME is too slow for shock formation.

Solar Rotatpon Dipole Axis

The evolution of the solar wind speed with distance can be understood with reference to Figure 4.15. Consider a spacecraft at constant heliographic latitude (e.g., the equator) as the Sun rotates under it. As the Sun rotates, the solar wind arriving at the spacecraft will change from slow to fast when the longitude of the boundary becomes the same as the heliographic longitude of the spacecraft. Fast wind will then arrive until the opposite side of the Sun rotates into view and the boundary again crosses the longitude of the spacecraft and fast wind is replaced by slow wind. If the tilt angle is sufficiently large, both the north and south boundaries can be crossed twice, so that the pattern becomes slow then fast wind from the north followed by slow then fast wind from the south. The HCS will be crossed twice inside the slow wind. Figure 4.16. Schematic and observations of a CIR at large distances. The magnetic field magnitude and solar wind speed were observed by Pioneer 10 at 4.3...

Diving Through an Atmosphere

In 1995 NASA's Galileo orbiter arrived at Jupiter. It carried a 339-kilogram (747-pound) probe that was ejected to descend into Jupiter's atmosphere. Once decelerated to a mere 100 kilometers (62 miles) per hour by the atmospheric drag, the probe ejected its protecting heatshields and continued to descend for about an hour, measuring gas compositions, temperatures, pressures and wind speeds. At a depth of 130 kilometers (80 miles) the short but exciting mission ended abruptly when the Galileo entry probe was destroyed by a pressure of 25 times that on the Earth's surface and a temperature over 150 degrees Celsius (300 degrees Fahrenheit).

Ulysses Soho And The Origin Of The Suns Winds

Where do the Sun's winds come from Since spacecraft generally measure the solar wind streams near the Earth, far from their source on the Sun, scientists have to use other measurements to extrapolate back to the place of their origin. Comparisons of wind-velocity measurements with X-ray images of the Sun indicated, in the 1970s, that whenever a high-speed stream in the solar wind swept by Earth, a coronal hole rotated into alignment with our planet, ttis naturally suggested that at least some of the highspeed wind is gushing out of coronal holes on the Sun. Observations of the scintillation, or twinkling, of radio signals from remote radio sources indicated that the gusty, slow-speed wind comes from a different place, confined to low latitudes near coronal streamers when the Sun is near the minimum of its activity cycle. Ulysses has now completed a second orbit around the Sun, during a maximum in the 11-year cycle of solar activity, permitting a comparison of solar wind speed at...

Energetic Particle Populations In The Inner Heliosphere

An overview of the solar-minimum measurements by the low-energy particle instrumentation on Ulysses is shown in Figure 5.1. The intensities of 40-65 keV electrons and 1.8-4.7 MeV ions from HI-SCALE (Lanzerotti et al., 1992), and 71-94 MeV protons from the High Energy Telescope (HET) of COSPIN (Simpson et al., 1992) are plotted in the upper three panels of Figure 5.1, respectively, as a function of time throughout the solar minimum orbit. The fourth panel of Figure 5.1 shows the solar wind speed, whereas the bottom panel shows the heliographic latitude (blue line) and the heliocentric radial distance (red dashed line) of Ulysses together with the monthly sunspot number (green hatched area). Figure 5.1 spans from 22 August 1992 when Ulysses was at the heliocentric radial distance R 5.28 AU and heliographic latitude A 15.8 S to 30 October 1998 when Ulysses was at R 5.29 AU and again at A 15.8 S, therefore this period includes the first perihelion at 1.34 AU on 12 March 1995 and the...

On the formation and origin of fieldaligned ion beams

ISEE observations have provided well-documented characteristics of field-aligned ion beams, with most of them observed at QSn 70o. Studies by Paschmann et al. (1981) and Bonifazi and Moreno (1981) suggested that the characteristics of these beams are largely independent of QBn. Typically they show an average flow speed which is on the order of twice the solar wind speed, but sometimes it can be significantly higher. Their density reaches up to about 1 of the solar wind, but it can be much smaller. Paschmann et al. (1981) found that these beams consistently exhibit a temperature anisotropy (T T w 4-9), where T and T are the temperatures perpendicular and parallel to the magnetic field. The perpendicular temperature is usually much larger than the solar wind temperature, which is in the keV range. Beams at larger shock normal angles (QBn 70 ) have been observed reaching much higher energies. Their bulk speed was higher by a factor of 5 (or even larger) than the solar wind bulk flow....

PTT PnnV Vpn vun VVuJ3

Un wind velocity QE Earth's angular velocity The subscripts n and i refer to the neutral and ionized components of the upper atmosphere, respectively. Evidently, this equation describes an equilibrium situation in which the inertial forces due to temporal and spatial changes in the wind velocity field are just balanced by the pressure gradient force, the viscosity force, the gravity force, the frictional force, and the Cori-olis force. Besides the wind velocity un, which is of primary interest here, this equation contains a number of variables which must either be eliminated using, for example, the continuity equation and the ideal gas law, or which must be specified beforehand. For example, the pressure gradient force may Another family of models exists which simulates both the neutral and ionized upper atmosphere self-consistently, sometimes even including the plas-masphere. In these models the non-linear balance equations of density, momentum, and energy are solved simultaneously....

Diffuse Ion Acceleration

Since the early observations of ions upstream of Earth's quasi-parallel bow shock by Asbridge et al. (1968) and by Lin et al. (1974) upstream ions with energies just above the solar wind energy up to several hundred keV have been under investiga- charge, and the ratio of the fluxes of the two species is constant as a function of energy per charge (Ipavich et al., 1981). The distribution of diffuse ions is rather isotropic with a shock directed bulk velocity slower than the solar wind speed. Hoppe et al. (1981) demonstrated that there is a one-to-one correlation between the presence of diffuse upstream ions and the occurrence of hydromagnetic waves in the foreshock region. This has led to the widely adopted picture of an intensive interplay between the waves and energetic ions the waves are thought to constitute scattering centres for the ions, which results in a diffusive transport. If transport is diffusive these particles will experience the shock compression, which leads to first...

Interactions with the Atmosphere Mass Balance Processes

Ablation is thought to occur by sublimation of H2O vapour due to insolation and wind erosion. The sublimation occurs during summer and is controlled by surface temperature and wind speed. The Martian atmosphere is thin and the atmosphere is readily saturated. Therefore, wind transport of vapour from the cap constitutes an important control of the sublimation from the cap.

Summary of Chapters 5 and

It was demonstrated that certain aspects of solar activities and their consequences on the magnetosphere can be studied and understood better in terms of the magnetic field distribution on the source surface than complicated photospheric features. The late declining phase was chosen, so that the neutral line has a single sinusoidal (or rectangular) structure, and the solar wind speed and geomagnetic disturbances are highest during the sunspot cycle. 4. By introducing a new coordinate (NESW) system, it was shown that the location of the two hypothetical dipoles coincides approximately with the nest of the solar flares, the brightest region of corona and also the source of the lowest solar wind speed. Thus, the two hypothetical photospheric dipoles are realistic physical entities. Figure 6.18 summarizes all the results in this chapter. Magnetic Equator Corona Solar Wind Speed Flare Triple Dipole Model Magnetic Equator Corona Solar Wind Speed Flare Triple Dipole Model

Predicting The Weather September

These sites allow you to zoom in on your local area to get information, from simple cloud forecasts with temperature, wind speed, pressure and likely rain patterns to satellite images. Satellite images are handy for showing the current atmospheric conditions in both visual and infrared light, and how they may develop over the following hours. One website even predicts the seeing for your area (www.meteoblue. com). The lower the seeing in arcseconds, the better. Forecasting on the day is the most reliable method as cloud cover changes very quickly. There are also barometric pressure charts. These are useful weather indicators, with high pressure indicating clearer conditions and lower pressure warning of unsettled conditions, cloud and stronger winds. Simple home weather stations can also tell you the current pressure, wind direction and speed. There is a strong correlation between good seeing and low wind speeds, irrespective of the atmospheric pressure.

Lamb Wave Uproots Trees

This study is primarily interested in the amplitudes of internal waves near the surface. As is well known, if the wind speed is 20 m-s-1, branches break from trees, whereas at wind speeds 25-30 m-s-1 (severe storms and hurricanes), trees break and are uprooted. Figure 5 shows that gas speeds no less than 30 m-s-1 are reached over the whole Earth's surface. Waves with a negative gas velocity are less subject to dispersion (Kshevetskii 1998).

The Future Forecasting Space Weather

The first approximation to help model the solar wind stream structure in the inner heliosphere may be provided through the so-called potential field source surface (PFSS) model in which the coronal magnetic field is assumed to be current free (rot B 0) (e.g., Hoeksema 1984, Wang & Sheeley 1992, Schrijver & de Rosa 2003). The data input for these models are ground- and space-based magnetograms. New magnetohydrodynamic (MHD) codes are also able to take to some extent contributions from active regions into account. The structure of the global solar corona has been calculated, e.g., based on the Magnetohydrodynamics Around a Sphere (MAS) model developed by the SAIC (Science International Corporation) group for the range 1-30 RS based on the strength of the radial magnetic field Br(0, y) as a function of solar latitude (0) and longitude (y) provided through full disk synoptic, i.e. the data cover the time period of a full solar rotation) magnetograms and temperature Te (0, y) and density...

ERS Earth Resources Satellite

Monitor Earth's oceans, ice caps, and coastal regions. The satellites provided systematic, repetitive global measurements of wind speed and direction, wave height, surface temperature, surface altitude, cloud cover, and atmospheric water vapor level. Data from ERS-1 were shared with NASA under a reciprocal agreement for Seasat and Nimbus 7 data. ERS-2 carries the same suite of instruments as ERS-1 with the addition of the Global Ozone Measuring Equipment (GOME), which measures ozone distribution in the outer atmosphere. Having performed well for nine years more than three times its planned lifetime the ERS-1 mission was ended on March 10, 2000, by a failure in the onboard attitude control system. The length of its operation enabled scientists to track several El Ni o episodes through combined observations of surface currents, topography, temperatures, and winds. The measurements of sea surface temperatures by the ERS-1 Along-Track Scanning Radiometer, critical to the understanding of...

Photoevaporation of

The appearance of MWC 349 again seems to call for a planar configuration of dusty gas. Note, however, that radio emission can penetrate dust without suffering extinction. The morphology of Figure 15.16 indicates rather a lack of ionizing gas in the equatorial region. A large column of dust would indeed absorb stellar photons and thus halt the advance of ionization. The enhanced absorption could arise from a slab or disk, a view that has been bolstered by the detection of near-infrared radiation from this central region. Note also that an ionized wind is present in the extended lobes, since the integrated radio flux has a spectral index aradio of 0.6, close to that predicted by theory. The wind velocity, gauged from the width of emission lines, is surprisingly low, only 50 km s-1.

Interplanetary Magnetic Field Ejected As Cmes

We need to know the date Tm of ejection of the solar wind encountered by NOZOMI. However, we had only limited opportunity to measure solar wind speed, so the date was estimated with the aid of AC.E SWEPAM measurements. The bottom diagram of Figure 1 shows the relationship of (a) the time TV of NOZOMI observation, (b) the time Ta of ACE observation, (c) the time Taq of launch of the plasma toward ACE, and (d) the time Tm of launch toward NOZOMI. The magnetic field observed by NOZOMI agreed well with the result from ACE shifted to NOZOMI position until November 10, 1999 disagreement started thereafter. Many of the CMEs on the east limb in the SOHO LASCO catalog correspond to the disagreement between NOZOMI and A CE observations. It is likely that NOZOMI encountered transient magnetic structures or that the heliospheric magnetic field re-structured after ejection of the CMEs, although the difference may be due to transients which passed ACE, or inaccuracy in solar wind speed...

Modeling the 11year and 22year cycles

A major issue with time-dependent modeling is what to assume for the time dependence of the diffusion coefficients, which is significantly more difficult to do from first principles than their energy or spatial dependence. A basic departure point (required to make progress) for the time dependence of the transport parameters to describe global long-term modulation is that propagating barriers (solar wind and magnetic field structures inhibiting the easy access of cosmic rays) are formed (and later dissipate) in the heliosphere during the 11-year activity cycle. The concept was first implemented in a model by Perko and Fisk (1983) and later extended by Potgieter and le Roux (1989). This is especially applicable to the phase of the solar activity cycle before and after solar-maximum conditions when large steps in the particle intensities have been observed. In fact, a wide range of interaction regions occur in the heliosphere, the largest being called global merged interaction regions...

The compound modeling approach to longterm modulation

A subsequent step in modeling long-term modulation came when Cane et al. (1999) and Wibberenz, Richardson, and Cane (2002) pointed out that the step decreases observed at Earth could not be primarily caused by GMIRs because they occurred well before any GMIRs could form beyond 10-20 AU. Instead, they suggested that time-dependent global changes in the heliospheric magnetic field over an 11-year cycle might be responsible for long-term modulation. Following the work of le Roux and Potgieter (1995), relating this approach to changes in the diffusion coefficients, Ferreira and Potgieter (2004) combined these changes with time-dependent drifts to simulate long-term in the inner heliosphere. They called it the compound modeling approach. It was assumed that all the diffusion coefficients change time dependently B(t)-n, with B(t) the observed magnetic field at Earth and n a function of rigidity and the current sheet tilt angle. The latter provides, from a cosmic ray perspective, a very...

Schatzmans braking mechanism

Where the indices A indicate that the wind speed v, the poloidal field strength H, and the density p are evaluated at r rA .In the simple model developed by Weber and Davis (1967), where the magnetic field in the thermally driven wind is approximately radial in the corotating frame of reference, the effective corotation prescription gives the following expression for the angular momentum loss rate

Satellites for sale the fourteenth Shuttle mission

Excessive wind speed between the 20,000- and 40,000-foot levels. All was fine the following day, 8 November, with Discovery making its return to space without incident. The two commercial satellites were deployed by the crew during FD 2 and FD 3, with Allen managing the deployment of Anik D2 and Anna Fisher deploying Leasat 2 the next day. The precise chase to reach the two stranded satellites deployed from STS 41-B passed without incident and the two resulting EVAs (6 hours on 12 November and 5 hours 42 minutes on 14 November) successfully brought both rogue satellites back into the payload bay of the orbiter for the journey home. After the completion of a number of mid-deck experiments, Discovery returned to Earth with the two satellites safely aboard on 16 November, after a flight of 7 days 23 hours 44 minutes 56 seconds, during orbit 127. Flight Director Jay Greene highlighted the huge achievement of the mission by saying ''We've deployed satellites before we've picked up...

Sample Analysis at Mars SAM

In addition to this suite of scientific instruments on the MSL, there are two additional instruments. The Dynamic of Albedo Neutrons (DAN) instrument will be used to detect subsurface water or ice. Frozen or liquid water absorbs and slows neutrons escaping from the planet's surface as a result of cosmic ray activity more than other substance. These slower neutrons will be measured by the DAN in an effort to find this key element of biological life. It will be sensitive enough to detect water ice content as small as one-tenth of one per cent. Scientists estimate that water ice may constitute from thirty to fifty per cent of the subsurface deposits near the Martian's poles. The Rover Environmental Monitoring Station (REMS) will act as the MSL's weather station, monitoring wind speed and direction, atmospheric pressure, humidity, temperature and ultraviolet radiation from the Sun. This instrument will be mounted on the MSL's mast assembly. The Centro de Astrobiologia in Spain will...

Collapse Observations

Measurements of narrow cavitons in the solar wind are very difficult, since the cavitons propagate at the speed of ion-acoustic waves, which is much lower than the undisturbed solar wind speed, cia vsw. Hence, direct measurements of structures only a few Debye lengths wide and blown across the spacecraft at the solar wind speed are impossible at the currently achievable time resolution. However, because the cavitons have a broad k-spectrum, broadband spikes of electrostatic low-frequency waves

The Sun and the solar cycle

The quasi-dipolar nature of the Sun's magnetic field over the majority of the solar cycle has the consequence for the 3-D heliosphere that the average solar wind speed increases with magnetic latitude. Shortly after solar maximum, when coronal holes have grown over the magnetic poles, an average speed increase with latitude was expected and interplanetary scintillation measurement showed this to be the case (Coles et al., 1978).

Model and Tomographic Analysis

The heliospheric model in our analysis and the iterative procedure that provides the three-dimensional results are explained more thoroughly in Jackson et al. (1998). The UCSD tomography program currently applies corrections to a kinematic model, modifying the model until there is a least squares best fit match with the observations. The solar wind model provides two parameters to fit in three dimensions the radial outward solar wind velocity and the solar wind density as described previously. Density rather than the small-scale density variations are used in the IPS analyses and propagated outward in the UCSD kinematic model, and thus density is related to density variation as in (17.5), to be used in the LOS integral. IPS velocity is related to its perpendicular component, as in (17.6), and used in the LOS integral as well. In the Thomson-scattering case, density is related to brightness directly in (17.7) and used in the LOS integral.

Structure of the Heliosphere

The structure of the inner heliosphere near solar minimum resembles the skirt of a ballerina as proposed by Alfven in (1977) and sketched in Fig. 1.7. At some solar radii distance from the Sun the solar wind in both hemispheres is comprised of the two flows from the large polar coronal holes with opposite magnetic field polarity, yielding a so called two sector structure of the IMF. An observer, e.g., at Earth orbit, would pass through the upper and lower parts of the ballerina skirt during one solar rotation, i.e. would record phases of opposite polarity of the IMF. For a typical solar wind speed around 450 km s, based on the rotation period of the sun, the interplanetary magnetic field lines form the shape of an Archimedean (Parker) spiral with an average direction of 135 as measured counterclockwise with respect to the sunward direction. A detailed review on the physics of the inner heliosphere has been provided by Schwenn & Marsch (1990, 1991). CIRs are important triggers of...

Northern And Southern Lights

Even though changing conditions on the Sun may trigger the intense northern and southern lights, we now know that the electrons that cause the auroras arrive indirectly at the polar regions, from the Earth's magnetic tail, and that these electrons can be energized and accelerated locally within the magnetosphere. Changing solar-wind conditions can temporarily pinch off the Earth's magnetotail, opening a valve that lets the solar-wind energy cross into the magnetosphere and additionally shooting electrons stored in the magnetic tail back toward the aurora zones near the poles.

Predicting The Atmo Calms

The popular concept of an astronomer's perfect night is one where a cold front has swept through the observer's location and a crystal-clear sky full of twinkling stars can be seen. In fact, this is a nightmare scenario for the planetary observer. A cold front passing through a region may well reduce the moisture content of the air and is great for looking at deep sky objects and comets, but it leaves the air in a very unstable state and, invariably, the hotter ground radiates its daytime heat into space, further increasing the chaos in the atmosphere. At high powers, the Moon and planets will be a wobbling, distorting mess. What is required for the best planetary views is stability, and this invariably comes from the presence of a high-pressure system anchored over the region. In a high-pressure system, especially one that has been around for a few days, the air becomes hazy (and polluted in cities) but it is very stable. The ultimate in atmospheric stability is often achieved when...

Open versus closed magnetosphere

Arnoldy (1971) correlated the AE index, a quantitative measure of auroral zone magnetic activity (Davis and Sugiura, 1966), with Bs, which is set to zero for IMF Bz 0 and to Bz for southward orientation of Bz. On the basis of hourly averages a correlation coefficient of 0.8 was obtained, while other solar wind variables produced coefficients 0.4. Further studies introduced more refined coupling expressions (e.g., Perreault and Akasofu, 1978 Bargatze et al., 1985) for instance, Bs was replaced by the dawn-dusk electric field component FswBs (Burton et al., 1975), where Fsw is the solar wind velocity. All studies, although varying in details, confirmed that the southward directed IMF component plays a central role in determining the strength of energy coupling between the solar wind and the terrestrial magnetosphere (Bargatze et al., 1999), so that these (as many other) observations are in conflict with the closed magnetosphere model.

Magnetic Braking of Rotating Stars

For other geometries, the exponent n is different 279 . Co-rotation of the stellar wind is present up to a radius rA where the Alfven velocity vA (Sect. 13.1.3) is larger or equal to the wind velocity v. This means that up to this point the magnetic field dominates the dynamic of the wind. The wind velocity is currently a multiple wind of the local escape velocity. These two velocities are, respectively,

Coronal mass ejections

Another ICME signature is the O7+ O6+ charge-state ratio, which has already been used for the separation of the two quasi-stationary solar wind types (although, as argued above, the C6+ C5+ ratio would be superior for that purpose). Of course, in the light of the above paragraph it comes as no surprise that O7+ O6+ is often enhanced in ICMEs. This was already found by Neukomm (1998) and by Henke et al. (2001), who found a good positive correlation of the presence of a magnetic cloud, a sure ICME identifier, with high O7+ O6+. However, the definition of a clear-cut threshold value is much less evident in this case than it is for (QFe). Richardson and Cane (2004) overcame this difficulty by defining a solar wind speed-dependent threshold value instead of a constant one. From observations with ACE-SWICS they determined a correlation between O7+ O6+ and the solar wind speed (in units of km s) (O7+ O6+)ACE03 3.004 exp( V 173) to hold in the ambient solar wind away from all ICMEs, and...

The Low Speed Solar Wind at High Solar Activity LSA and its Sources

Polar plots of solar wind speed as a function of latitude of Ulysses' first two orbits. Sunspot number (bottom panel) shows that the first orbit occurrred through the solar cycle declining phase and minimum while the second orbit spanned solar maximum. Both are plotted over solar images characteristic of solar minimum (8 17 96) and maximum (12 07 00) from the center out, these images are from the Solar and Heliospheric Observatory (SOHO) Extreme ultraviolet Imaging Telescope (Fe XII at 195 A), the Mauna Loa K-coronameter (700-950 nm), and the SOHO C2 Large Angle Spectrometric Coronagraph (white light). From McComas et al. (2003). Figure 5. Polar plots of solar wind speed as a function of latitude of Ulysses' first two orbits. Sunspot number (bottom panel) shows that the first orbit occurrred through the solar cycle declining phase and minimum while the second orbit spanned solar maximum. Both are plotted over solar images characteristic of solar minimum (8 17 96) and maximum...

Solar wind magnetic field and the current sheet

Apart from the diffusion coefficients all cosmic ray transport models also require knowledge of the global structure and geometry of the heliosphere, the heliospheric magnetic field, the current sheet, and the solar wind velocity. Observations by the Pioneer, Voyager, Ulysses and other spacecraft have contributed significantly to understanding the spatial dependence and time evolution of these features. A major contribution was the confirmation that V is not uniform over all latitudes but that it can be divided into fast and slow solar wind regions during solar-minimum conditions (McComas et al., 2000).The latitude-dependent radial solar wind speed inside the termination shock can be approximated for modeling purposes by

Inner Magnetospheric Convection

During times of geomagnetic disturbance, sunward plasma convection (or advection), plays a crucial role in plasmaspheric dynamics. Perhaps the most fundamental cause of inner magnetospheric convection is dayside magnetopause reconnection (DMR). The magnetopause is the boundary between the geomagnetic field and the interplanetary magnetic field (IMF), nominally found at subsolar distance 10 Re. When the IMF at the magnetopause is oriented opposite (southward) to the geomagnetic field, these oppositely-directed fields can undergo reconnection, a process that causes dayside geomagnetic field lines to become joined to the IMF lines, which then are dragged antisunward (along with the prevailing solar wind flow) into the stretched out magnetospheric tail (magnetotail). This magnetic flux transfer drives sunward convective flows in the inner magnetosphere (Dungey, 1961). Associated with this sunward convection is a solar-wind electric (E) field that points from dawn to dusk, with magnitude...

Magnetopause Structure

Mariner 10 data indicated that the Mercurian magnetopause had a significant aberration in the ecliptic plane as well as equator-pole asymmetries. Ness et al (1975) computed the shape of the magnetopause for the case where the solar wind was incident on a Mercury-centered magnetic dipole orthogonal to the solar wind flow. The theoretical position of the bow shock was determined for the case of aligned flow, in which the upstream magnetic field and solar wind velocity were deemed to be parallel. A sonic Mach Number 10 and an AlfVen Mach Number 20 at the subsolar point were

Active Regions Coronal Holes and the Solar Wind

Returning to the sun, we usually find that the predominant magnetic field polarities within the large unipolar regions in the southern and northern solar hemispheres have opposite signs. Opposing fields from the large unipolar regions tend to reconnect at a great distance from the sun producing a neutral sheet in the neighborhood of the ecliptic plane. Looking down on the pole, a sector structure of the IMF is observed, with the magnetic field polarity in adjacent sectors being reversed. This interesting feature is the result of a latitudinal undulation in the neutral current sheet that, under quiescent conditions, would reside in the neighborhood of the ecliptic. The solar wind speed is greatest away from sector boundary crossings. Wind speeds may vary from 700 km sec during disturbed times and within the center of a sector, to 300 km sec in the neighborhood of a sector boundary crossing. Greater wind speeds cause more significant ionospheric effects. Measurements of the IMF and the...

Icme Magnetic Clouds Nose

14 35 UT, labelled with a solid thick line. Several hours later on the same day at around 19 UT it was followed by the ICME as identified from the unusual high magnetic field strength and smooth southward to northward rotation of the magnetic field direction with respect to the ecliptic plane. The rotation started on July 15 at about 19 UT and lasted until July 16, 09 UT. At the top of Fig. 1.24, Kp-values greater than 7+ are listed in the corresponding 3-hour intervals. The time-period of the strongest magnetic disturbances measured at Earth corresponds with the time interval of the occurrences of the strong southward magnetic field components caused by the ICME, even without taking details of the WIND orbit into account. The magnetic storm starts with the arrival of the shock wave triggering turbulent IMF fluctuations, followed by its main phase at times of the southward directed magnetic field at the leading edge of the ICME. The magnetic field strength at the nose of an ICME is...

Ion Wind Chamber Design

Magnetic field strength Proton density Solar wind speed Proton temperature Alfv n Mach number Sonic Mach number Proton gyroradius N+ gyroradius Ion inertial length Electron inertial length Cassini was the first spacecraft to measure pickup ions in the interstellar medium downstream region of the heliosphere beyond 1 AU (McComas et al. 2004a). Both interstellar pickup H+ and He+ were identified with the familiar cutoff in velocity space at twice the solar wind speed. Observed enhancements in the pickup He+ were consistent with gravitational focusing by the Sun. Further, McComas et al. also reported observations of the interstellar hydrogen shadow from depletion of H atoms in the downstream region caused by the outward force of radiation pressure (which exceeded the gravitational force at the time of observation) and the high probability of ionization for atoms that must pass close to the Sun to move behind it.

Corotating Interaction Regions CIRs

The origin of the fluctuations in Bz (i.e. the solar magnetic field in the North-South direction) has been revealed by studies using data from the Ulysses mission. Cross correlation analysis of fluctuations in B and the solar wind velocity showed high correlation at zero lag, demonstrating that they are Alfven waves. Alfven waves occur when the vibration of the magnetic field part of the wave is perpendicular to the direction of travel of the wave.

Initial mass of M 11 Mq

The approximate structure of the massive star after the silicon has been exhausted in the core is shown in Fig. 1.6. The star consists now of several layers of different composition that are separated by thin nuclear burning shells. The details of the nucleosynthesis are complicated and will be discussed in Chapter 5. It is sufficient to mention at this point that the heaviest and most stable nuclei (that is, the iron peak nuclei Section 1.3) are found in the core. In fact, the most abundant nuclide in the core is 56Fe. It should also be noted that the luminosity during the red giant phase is so large that the star undergoes a significant mass loss. The effect is more pronounced for stars with M 30-35 Mq that lose eventually most of their hydrogen envelope. The observational counterparts of such stars are the hot and massive Wolf-Rayet stars, which have been observed to lose mass at a rate of & 10 5 Mq per year at stellar wind speeds of & 2000 km s. An image of a Wolf-Rayet star is...

From Arming Tower to Mobile Service Structure

Wind loads were a second major concern for the tower's designers. On 28 March representatives of the Marion Power Shovel Company, the Corps of Engineers, LOC, and Rust agreed to design for a maximum wind velocity of 100 kilometers per hour. When resting on its supports at the launch pad, however, the arming tower was to be able to sustain considerably higher winds. NASA officials cancelled the latter requirement two weeks later in the event of a hurricane, the tower would be removed from the pad area.42

The Wardle Instability

Returning to the Orion BN-KL region, the H2 emission has features that remain problematic, at least for the simplest C-shock models. The individual lines tend to be quite broad, with velocity widths often exceeding 100 km s-1. A planar C-shock normal to the flow can yield emission over a range of velocities, depending on the actual speed of the preshocked gas. The total range of velocities, however, cannot exceed the upper limit to V hock of about 50 km s-1. On the other hand, suppose that gas enters the planar shock obliquely. Then the velocity component parallel to the front is preserved. This component could easily exceed 100 km s-1, depending on the wind speed and the orientation of the shock relative to this flow. Broadened lines could then be produced by the superposition of many such oblique shocks, each with a different orientation i. e., from a curved, rather than planar, shock front. Over part of the curved surface, the impact speed could be high enough to result in a...

Planetographic Latitude

The first example is a study of the behavior of the zonal wind. By observing the motions of cloud features in images obtained with the Voyager television cameras, zonal wind speed has been derived as a function of latitude. The level of the visible clouds to which the wind speeds pertain is not known with certainty however, it is believed to be in the 500-700 mbar region. A series of alternating eastward and westward jets is observed. Estimates of the Rossby number are less than unity, which suggests that the zonal thermal wind relation, Eq. (9.2.29), should be valid. Application of this relation to the thermal structure for Jupiter, shown in Fig. 9.2.6, yields the thermal wind shear as a function of latitude, shown in Fig. 9.2.7. Also displayed is the wind speed, obtained from the cloud motions as a function of latitude. Comparison of the wind speed and the vertical shear indicates a tendency toward anticorrelation, which implies that the wind speed decreases with height. Similar...

Figures

3.12 Polar plots of the solar wind speed and the oxygen charge-state temperature 61 4.24 The field directions inside a CRR based on a model in which the solar wind speed varies along field 5.1 Daily averages of 40-65 keV electron intensities 1.8-4.7 MeV ion intensities 71-94 MeV proton intensities solar wind speed and monthly sunspot number. 6.17 6-hour averages of MeV protons, keV electrons, compositional signatures of the solar wind, galactic cosmic rays, magnetic field, and solar wind speed from 10 January 1993 to 9 February 1993 222 6.27 Measured and modeled solar wind speeds 234 7.2 Dial plots of solar wind speed and density, with co-temporal coronal images, during O-I and 253 7.4 Solar wind speed, oxygen, and carbon ''freeze-in temperatures'' in a CIR and abundances of low FIP elements Fe and Si relative to O 263

Filters

The solar wind velocity is the single most important interplanetary input to the radiation belts. The relative importance of this parameter can be assessed by measuring the higher prediction capability of electron flux dynamics using the VSW input compared to any others. The significance of VSW was determined early on through comparisons between VSW and subsequent relativistic electron fluxes at geosynchronous orbit e.g., Paulikas and Blake, 1979 . Physically, increases in VSW lead to momentum and energy transfer on the dayside through compressions and at the magnetospheric flanks through shear-flow instabilities such as Kelvin-Helmholtz e.g., Farrugia et al., 2001 . The effects of the viscous processes are most clearly observed under conditions of a zero or weakly positive IMF Bz. In either scenario, the compression or instability drives ULF waves such as Pc5 (period of 2-10 min) into the magnetosphere Anderson et al., 1990 Engebretson et al., 1998 Vennerstrom, 1999 . The waves grow...

Precursors

For an externally driven system like the radiation belts, determining the geoeffective precursor activity is a more direct method than filter analysis for forecasting and modeling. The precursors to an electron acceleration event can be physically interpreted as structures in the solar wind. We briefly sketch out below the precursor analysis which is described at length in Vassiliadis et al., 2003 a . We denote the daily average J(ti Lj) as an event of that amplitude at shell Lj. The precursor to that event, in terms of the solar wind velocity, is the activity vector Second, the precursors for P1 and P2 have opposite orientations in solar wind velocity VSW and density pSW. In addition the P1 precursor has a Southward IMF Bz (middle panel of Fig. 7), consistent with energization through dayside reconnection and, eventually, production of seed electrons. The P2 precursor is characterized by a Northward IMF Bz., producing a weak reconnection poleward of the cusp. Acceleration in the cusp...

Background

Oceans are a growing source of energy - oil and especially natural gas - as operators reach into the seafloor in deeper and deeper parts of the ocean with multibillion dollar facilities. Offshore wind farms would also depend on timely, reliable information on ocean conditions. Better ocean observation will help harness various energy sources safely and efficiently with minimal environmental impact.

A 35 M0 star

In the RSG stage the wind velocity falls to a low value of about 75 km s, whereas the mass loss rate jumps up to a few times 10-5 M0 yr. A new pressure equilibrium is established, and a RSG shell is formed in the interior, which is also unstable to thin-shell instabilities. Fig 8.5 (frames 1 and 2) shows images of the density during the RSG evolution. The wind velocity in the WR phase climbs back up to almost 3000 km s, whereas the mass loss rate drops by only a factor of a few from the RSG stage. The momentum of the WR wind is then about an order of magnitude larger than that of the RSG wind, and the wind pushes the RSG shell outwards, simultaneously causing it to fragment (Fig 8.5, frame 3). The RSG wind material is mixed in with the rest of the MS material (Fig 8.5, frame 4), a key result since the RSG wind velocity was so low that the material by itself could not have gone very far. Out of 26M0 of material lost in the wind, about 19 M0 is lost in the RSG stage, so much of the...

Discussion

The grain sizes determined here are considerably larger than those determined by overall light curve shape modeling 11 . Radiation pressure forces from main sequence stars can only eject grains of this size from the most massive O and possibly B0 stars 7,19 , However, by our flare duration technique we cannot rule out the presence of smaller grains in addition to the larger ones needed to model the flare duration. Some authors 20 have assumed that the grains within each dustball meteoroid may follow the same mass distribution law as meteoroids themselves. An interesting question is whether dustball meteoroids may fragment in space, with their grains being subsequently ejected from the planetary system by radiation pressure forces. While this must occasionally occur, a consideration of the solar wind energy flux suggests that hundreds to thousands of Leonid orbital passages would be needed for a typical Leonid to remove the volatile component by solar wind sputtering. This is supported

Xray Lightcurve

We conclude that these changes in the X-ray lightcurve reflect changes of the density in the ambient matter profile, which appear to show some repetitive pattern like in a wave. Whether this characterizes the activity of the progenitor star with respect to mass loss or wind velocity remains to be seen.

A dipole plus a wind

What happens in that case Since the wind energy density exceeds that of the magnetic field, the wind pushes out the field, drawing the field lines outwards to the extent that they become nearly parallel to the equator and no longer return to the surface. In this way, the outgoing wind can flow along the field lines everywhere. This is sketched in Fig. 1.24, which shows a simplified solution of this problem 27 . Because the lines parallel to the equatorial plane come from opposite ends of the dipole, they represent magnetic fields having opposite directions. Hence, at large distances, the magnetic field direction changes abruptly at the equator. This implies that a thin sheet of current flows along the magnetic equatorial plane in a direction normal to the figure in three How is the wind velocity related to this magnetic structure Naively, one expects that the flow of the wind will be unimpeded and stationary everywhere except near the current sheet where complex geometry-dependent...

Aerodynamic Forces

The next question is, How can such a thin atmosphere produce aerodynamic effects on spacecraft that perturb their orbital motion (see also the discussion about drag forces on launchers in Chapter 5) The key to this is to realize that the aerodynamic force on an object is dependent not only on the air density but also on how fast the object is moving through the air. For example, we know that sufficient aerodynamic force can be exerted on a garden fence to knock it down in a winter storm, provided the wind speed is high enough. This force, known as dynamic pressure, actually depends on the square of the wind speed. If the wind speed doubles, the force on the fence increases by a factor of four (22), if it trebles the force is nine times as big (32), and so on. No wonder storm-force winds make short work of fences

Periodic Massloss

A constant a implies that the percentage change in flux is the same at all frequencies, and this is illustrated in Fig. 2 on which is plotted the fractional deviation of the observed flux density from the best-fit model curves in Fig. 1, as a linear function of time. Fig. 2 also highlights an apparent periodicity in CSM density enhancements, with the shock wave reaching the peak of the first at t 150 days, a second peak near 300 days, and hints of a third peak between 400 and 500 days. For an ejecta expansion velocity of 15000 km s-1 and a stellar wind velocity of 10 km s_1, this would imply a series of shells 0.006 pc apart, ejected every 600 years or so. This is much longer than standard stellar pulsation timescales, but is not inconsistent with the period between thermal pulses (C He shell flashes) in 5 10 M0 AGB stars 7 .

Bands of Atmosphere

The atmospheric bands that are Jupiter's most striking feature are the result of convec-tive motion and zonal wind patterns. Warm gases rise, while cooler gases sink. The location of particular bands appears to be associated with the wind speed on Jupiter at various latitudes.

Morphology

The morphology of the solar wind around the solar activity cycle is illustrated in Figure 3.2. It is remarkable how closely solar wind speed profiles reflect the shape of the underlying corona both at low and at high solar activity (left and right panels, respectively).2 Figure 3.2. Morphology of the solar wind during the solar cycle. Bottom panel Average and smoothed monthly sunspot number top panels polar plots of the solar wind speed as observed with the SWOOPS sensor on Ulysses during the two polar orbits completed so far, with the color of the speed curve indicating the magnetic polarity. The background images are composites of corresponding SoHO LASCO and EIT images illustrating the typical shape of the solar corona at minimum (top left) and at maximum (top right) activity. The difference of the solar wind speed distribution between the minimum and the maximum heliosphere is striking (adapted from McComas et al., 2003). Figure 3.2. Morphology of the solar wind during the solar...

Composition

The principal motivation for solar wind composition studies is twofold on the one hand, we seek to determine the composition of the outer convective zone of the Sun (as represented by the photosphere) in order to infer the composition of the protosolar nebula, as this represents the baseline from which the entire solar system was formed some 4.6 Gyr ago (cf. von Steiger et al., 2001, and references therein). On the other hand, composition differences between different solar wind types (or other reservoirs) are indicative for the conditions and processes where these reservoirs originate. Thus, composition studies naturally fall into two different types chargestate composition and elemental composition. Charge-state composition (i.e., the distribution of the different charge states of a single element) probes the conditions and processes in the corona at a temperature of the order of 106 K, whereas elemental composition (i.e., the abundances of the elements summed over all charge...

Opportunities

The University of Denver has continuously operated a modest weather station atop Mt Evans since January 1991. This station has been outfitted with sensors to measure temperature, barometric pressure, relative humidity, wind speed and direction, and battery voltage maintained by solar panels. The station's data logger has been programmed to poll the sensors every minute and report hourly averages, as well as minimum maximum values and standard deviations for that hour. The bulk of the data presented in this section has been acquired from this station. Partial gaps in the data sets are due to occasional sensor malfunctions during these periods. A pyra-nometer was added to the sensor package in June 1996. Although battery voltages, despite a voltage limiter in the circuit, can indicate the fraction of sunny hours, the pyranometer provided more direct sunshine statistics. Wind data has been examined and reveals average and maximum hourly wind speeds for the four seasonal periods...

Landing Sites

The weather is a major factor in whether the landing is at KSC, Edwards Air Force Base or if it is postponed until a later orbit. The weather conditions include the amount and height of any cloud cover, the visibility, the wind speed and direction and if any thunderstorms are in the vicinity. The angle of the Sun is also considered, in case it is in the pilot's eyes as they come in to land. The chosen landing site can be changed up to 90 minutes before landing. About an hour before landing a de-orbit burn slows the Space Shuttle enough to begin its descent. There are other emergency landing sites around the world, which are covered later in this chapter.

The Solar Connection

While most of the early works concentrated on relating white-light CMEs to IP shocks, recent studies have focused on the connection between white light CMEs and ICMEs (Lindsay etal., 1999 Gopalswamy etal., 2000,2001b, 2005b Schwenn et al., 2005). Lindsay et al. (1999) found a linear relation between CME and ICME speeds and confirmed that slow CMEs accelerate and fast CMEs decelerate as a result of interaction with the solar wind. Gopalswamy et al. (2000) quantified this acceleration using SOHO and Wind observations and improved it further using quadrature data from Solwind coronagraph and Pioneer Venus Orbiter (PVO) data (Gopalswamy etal., 2001b). The interplanetary acceleration a (m s2) was found to be related to the CME speed V (km s) in the corona as a -0.0054( V -406). Thus CMEs with V 406 km s accelerate, while those with V 406 km s decelerate. CMEs have constant speed when V 406 km s. The critical speed of406 km s was identified with the solar wind speed. Figure 7 shows the...

Other power sources

As on Earth, it may be possible to derive power from ambient sources other than sunlight. Wind power has been proposed for the Martian surface environment. Development models of a wind-powered rover for Venus were also built and tested in the Soviet Union during the 1980s (the KhM-VD and KhM-VD2, from VNIITransMash). The available power of the windstream relates to the air density and the cube of the windspeed (thus 8 times more power is available if the windspeed doubles). Exploitation of the mechanical power of wind for locomotion (via balloon, tumbleweed rover, etc.) appears more likely in the near term than for electrical-power generation. It may also be possible to exploit temperature changes (either diurnal changes on a lander, or the temperature change with depth in a deep atmosphere for a descent probe or balloon) to derive usable energy.

Focus

In another approach, the speed of the solar wind as it blows past the Earth has been tied to deep roots within the chromosphere. NASA's Advanced Composition Explorer, abbreviated ACE, spacecraft measured the wind velocity near Earth, while NASA's Transition Region And Coronal Explorer, or TRACE for short, was used to measure the time sound waves took to travel between two heights in the chromosphere, tte comparison indicated that the speed of the solar wind emerging from a given area of the solar corona could be estimated from the thickness of the underlying chromosphere. It is stretched thin and opened wide in coronal holes, with their open magnetic fields and fast, tenuous solar wind, but the chromosphere is compressed below magnetically closed regions associated with the gusty, slow dense solar wind outflow (Fig 6.16).

Go 90 120 150 180

Departure of the magnetic field direction from the Parker spiral. Ulysses data acquired within a Corotating Rarefaction Region (CRR) during the interval at the top of the figure were averaged over 1 minute and rotated from RTN coordinates into a coordinate system with the x-axis along the Parker spiral based on hourly measurements of the solar wind speed. The components were converted to the latitude angle, called 9 here, and azimuthal angle, 0, with the Parker spiral coinciding with 0 0. The top panel contains contours of constant probability with the maximum probability shown in red. The bottom panel is the corresponding histogram of the 0 angles. Both displays show a significant departure from the Parker spiral of about 30 and a slight southward displacement. The average of 0 is deviated toward the radial direction. (Murphy et al., 2002)

Longitude

Upper A sinusoidal magnetic equator and the associated solar wind speed distribution on the source surface. Lower Solar wind speed observation at an equatorial point (fixed in space) at a distance of 3.5 solar radii.* Figure 6.1. Upper A sinusoidal magnetic equator and the associated solar wind speed distribution on the source surface. Lower Solar wind speed observation at an equatorial point (fixed in space) at a distance of 3.5 solar radii.*

Empirical Modeling

As with the physics-based models, the key to making predictions about the state of the geospace environment is to understand the conditions in the solar wind. The top path in Figure 5 shows the typical prediction route where measurements of the solar wind density (p), velocity (V), and magnetic field (B) are propagated to the Earth. These measurements can be used to drive models to predict the MeV electron flux (Vassiliadis et al., 2002 Li et al., 2003), magnetic field configuration (Tsyganenko, 1995), ground magnetic field perturbations (Weigel et al., 2003), and the vast array of magnetic indicies (Kp, Ap, Dst, AE) (Boberg et al., 2000 McPher-ron, 1999 Klimas et al., 1998 Takalo and Timonen, 1997). In the bottom path data input is pushed back to the solar surface where observations of the photospheric magnetic field are used within the Wang - Sheeley - Arge (WSA) method (Arge and Pizzo, 2000) to determine the solar wind speed and limited information about the interplanetary magnetic...

Ray Supernovae

Here A (T) is the temperature-dependent plasma emissivity M is the progenitor mass loss rate vw is the wind velocity and vs is the shock velocity. If vs is known (generally from measuring the width of the broad Ha lines), then (M vw), the ratio between the mass loss rate and the wind velocity, can be determined at the radius r ( vst). If one assumes that for a typical supernova the progenitor wind velocity is 10 km s-1 and the average shock velocity is 104 km s-1, then every year over which X-ray observations span samples 10 000 yrs of presupernova evolution. Thus, the SN X-ray light curve traces the mass loss history of the star. For the oldest X-ray supernovae, it has been possible to trace the pre-supernova mass loss history for 25 000 yrs before the explosion.

CME Properties

CMEs are characterized by speed, angular width, acceleration, and a central position angle in the sky plane. Measured speeds range from a few km s to nearly 3000 km s (e.g., Gopalswamy, 2004 see also previous studies by Howard et al., 1985 and St. Cyr et al., 2000), with an average value of 450 km s (see Figure 5), which is slightly higher than the slow solar wind speed. The apparent angular width of CMEs ranges from a few degrees to more than 120 degrees, with an average value of 47 (counting only CMEs with width less than 120 ). The width and other parameters of a CME occurring close to the limb is likely to be the true width, whereas the width and source latitude of a CME occurring close to the disk center are severely affected by projection effects (Burkepile et al., 2004). CME acceleration is discussed in Section 4.

Nesw Longitude

The stable sinusoidal (or rectangular) wave configuration of the neutral line provides the basis of the double peak, per solar rotation, of the solar wind speed and of geomagnetic disturbances during the late declining epoch of the sunspot cycle. 6. The double peak structure, per solar rotation, in the solar wind speed and recurrent geomagnetic disturbances is a basic feature, but it is often obscured by various complexities on the Sun and the relative location of the Earth with respect to the heliographic equatorial plane.

Ozma Project

Those with hydrogen emission are called Oe stars, while those with ionized helium and doubly ionized nitrogen are of stars. Emission line and 'Of' behaviour increase with increasing luminosity. Ultraviolet (and even optical) p cygni lines reveal wind speeds of up to 4800 km s (3000 mi s) and mass-loss rates of up to 10 5 solar masses per year.

Ta003358b

As an example of how the RPA can be used to measure very small changes in beam energy, and hence solar wind speed, Figure 10 shows the count rate as a function of RPA voltages for a range of different ion beam energies taken with the flight electro-optics during instrument calibration (described in more detail in Sect. 4.1). A small subset of the full energy range of SWAP (990 to 1010 eV) is shown to highlight the energy resolution possible by this instrument. For each scan, the count rate is normalized to the rate when the RPA voltage is set at zero to take into account the differences in the ion beam flux. Differences in the ion energy as small as 1-2 eV are distinguishable at typical solar wind energies of -1000 eV. The electro-optic design is driven by the unique needs of the New Horizons mission to Pluto. A large-aperture instrument is required since the density of the solar wind falls off as the square of the distance from the Sun. At 32 AU, where we will encounter Pluto, the...

Afterglows

Wolf-Rayet stars are found to have winds with typical mass loss rate M 10-5Mq yr-1 and wind velocity vw 1000 km spending in a termination shock where the wind runs into the surrounding medium 5 . A steady wind produces a density distribution p Ar-2 the value of the density can be scaled to the corresponding value for the standard wind parameters, A* A (5 x 1011 gm cm-1). For a surrounding medium of pressure p, the wind termination shock occurs at a radius

Surface Waves

Variations in the upstream solar wind velocity, in solar wind pressure, and in the interplanetary magnetic field act on the magnetopause boundary so that it is almost continuously moving as the equilibrium between total pressure on either side is dynamically restored. Boundary motion can induce anything from large-amplitude surface waves down to small-scale waves or ripples (Kivelson and Chen, 1995 Seon et al., 1995 Sibeck, 1990 Sibeck et al., 1991). Sckopke et al. (1981) presented in situ observations of boundary waves and discussed different possible topologies depending on the waviness of the magnetopause and of the boundary layer inner edge.

Waves and turbulence

The solar wind velocity vw introduces a complication the wave frequency is measured on a spacecraft that is generally moving at a small velocity (compared to vw) with respect to the Sun, and therefore at a velocity of about vw relative to the medium. As a result, a wave of angular frequency w and wave vector k is observed at a frequency w k vw, so that the relative Doppler frequency shift is Aw w vw v , where v is the phase speed. This shift is especially important for acoustic and MHD waves whose phase speeds - of the order of magnitude of the sound and Alfven speeds - are much smaller than vw. transformed into spectra in the wave vector component k along vw by the transformation k u vw 2nf vw this means that 1 second corresponds to a wavelength of the order of several hundreds kilometres - the solar wind speed. For example, the slow to fast wind changes that occur roughly once every 10 days (Fig. 1.18) contribute to the spectral density of fluctuations at frequencies around 10 6 Hz.

Ibi Fgm Sc2

The cusp is entered abruptly at 20 00 UT with a large decrease in the magnetic field strength, and rotation of the field. The cusp exit occurs at 20 08 UT with an enhancement in the magnetic field there is a cusp re-entry seen at 20 12 UT, after which the spacecraft are in the plasma mantle region. The plasma parameters show no such abrupt change, and decay slowly to and after 20 30 UT. This encounter differs considerably from the two discussed above. It is clearly dominated by the southward IMF and high solar wind speed which are likely to be driving strong low-latitude magnetopause reconnection. This in turn leads to convection of magnetic field lines through the cusp so that there is no evidence for stagnant plasma as

Spacefleet SF01

The Spacefleet Project, based in southern England, plans to build a fleet of three environmentally friendly spaceplanes powered by liquid hydrogen and liquid oxygen. Not only are these the best rocket fuels around, but they can be produced by electrolysis of water using a solar photovoltaic array and or wind energy. In this way, producing the propellants is a perfectly clean process, as is burning them in the engines, since the only combustion product is water vapor. The Spacefleet Project claims that its spacecraft is the only one under development known to inject zero carbon emissions into the atmosphere. Furthermore, production of these clean, energetic propellants is free and sustainable once the equipment is up and running.

Surfaces

Photographs from the surface show angular rocks. This was surprising, since it was expected by some that the thick atmosphere would lead to considerable erosion, smoothing the rocks. However, a very low wind speed has been found on the surface, so the erosion is not as great as originally thought. The soil is basalt, providing additional evidence of volcanic activity. The surface temperature is roughly constant at 750 K.

Magnetometer Sensors

A neutral mass spectrometer fed by two inlets in the forebody would measure the chemical and isotopic composition at various depths. In addition to the most common atomic species, this instrument would seek noble gases such as argon, krypton and xenon, and attempt to confirm whether (as hypothesized on the basis of the Voyager remote sensing) methane and ammonia reacted with lightning to create more complex organic molecules. An atmospheric structure instrument would measure the temperature, pressure, density and average molecular weight over a broad range of altitudes. In addition to being transmitted to the orbiter, its data would be used in situ as a reference for the other instruments. A nephelometer would determine the size, density, shape, etc, of cloud droplets by firing an infrared laser across a gap to a short arm carrying five mirrors that would reflect the beam back to the instrument. A net-flux instrument consisting of two radiometers, one...