Wind Phenomena Research Articles

Wind phenomena in the Dischma valley during DISKUS

The three-dimensional wind field of a small Alpine valley is analysed for two summer days. It is possible to evaluate the well-developed valley wind from measurements of the temperature in the valley atmosphere, the upslope wind from measurements of the temperature and the sensible heat flux in a satisfactory manner. Vertical profiles of the along-valley and across-valley wind components are given for a cross section of the valley at three positions for different times of day.

Analyses of experimental observations of electron temperatures in the near wake of a model in a laboratory‐simulated solar wind plasma

Laboratory experiments have been performed that show the effect on the electron temperature of inserting a spherical conducting model, larger than the Debye length, into a free‐streaming high‐energy (1 kv) unmagnetized hydrogen plasma. These experiments are the first electron temperature experiments conducted at energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. The incident plasma parameters were held constant. A large number of axial profiles of the electron temperature ratios Tein/Teout behind the model downstream in the model wake are presented. A rigorous statistical approach is used in the analysis of the electron temperature ratio data in both our experimental laboratory data and in our reanalysis of the published data of others. The following new results are obtained: (1) In energetic plasma flow there is no overall temperature enhancement in the near wake since the best fit to the Tein/Teout data is a horizontal straight line having a mean value of 1.05; (2) No statistically significant electron temperature enhancement peaks or depressions exist in the near‐wake region behind a model at zero potential in a high‐energy plasma even at distances less than or equal to Ma, where M is the acoustic Mach number and a is the model radius. This implies a “filling in” of electrons in the wake region which may be due to the higher mobility of these energetic electrons. This mechanism may permit the solar wind electrons to significantly contribute to the maintenance of the nightside ionosphere at Venus.

Low-frequency Jovian emission and solar wind magnetic sector structure

The Earth, Jupiter and Saturn emit non-thermal low-frequency radiations with similar characteristics. For the Earth and Saturn, the radio emissions are known to fluctuate with a time scale of several days, correlated with variations of the solar wind or related phenomena at the planet1–4. Several studies of the jovian radiation at decametre wavelengths, from ground-based observations, suggest that the non-Io-controlled emission fluctuates in response to the sector structure of the interplanetary magnetic field5–9. We study here the long-term fluctuations of the jovian emission at hectometre and kilometre wavelengths. We use observations from the Planetary Radio Astronomy (PRA) experiment aboard the two Voyager spacecraft. We show that these emissions are strongly affected by the magnetic sector structure at Jupiter. This leads us to discuss the position of the sources of emission in the jovian magneto-sphere.

Observations of structuring in the downstream region of a large spherical model in a laboratory simulated solar wind plasma

Laboratory experiments have been performed that show the effects of inserting a spherical conducting model, large in comparison with the Debye length, into a free streaming high‐energy (1 kV) unmagnetized hydrogen plasma. These experiments are the first laboratory measurements at energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. The incident plasma parameters were held constant. Transverse profiles of the net Langmuir probe current, plotted at various locations downstream in the model wake, are divided into three regions—the ‘shadow,’ the ‘transition,’ and the ‘boundary.’ The following new results are obtained: (1) enhancements in the ‘shadow’ exist at downstream locations where the Mach ratio is less than one; (2) turbulence exists in the ‘transition’ region on the shadow edges and outside in the ‘boundary’ region. These results appear to be attributable to the use of a high‐energy plasma for these studies. A small current enhancement is also present in the boundary and is attributable to the plasma/model interaction, in close agreement with low‐energy plasma/model interaction experiments. We speculate that many similar features observed by in situ spacecraft downstream from planetary bodies are relatively permanent and are due to the intrinsic nature of the interaction between the solar wind plasma and the obstacle rather than to transitory effects caused by the presence of discontinuities or other transitory characteristics associated with the flow.

Pulsed Doppler Radar Detects Weather Hazards to Aviation

Over the last several years experiments were conducted with a pulsed Doppler radar that have significant consequences for hazard detection in the en route and terminal areas. Mesocyclones can be detected to over 250 km while tornadoes are seen to about 150 km. The radar can detect strong straight winds if they have a significant component along the beam. It is definitely demonstrated that aircraft measured turbulence correlates with the spread of the Doppler spectrum, but caution must be exercised in interpreting the Doppler spectrum width data because these are more prone to gross errors due to noise, antenna sidelobes, ground clutter, etc. Measurements of transient wind phenomena associated with thunderstorms near the airport require a suitably located radar, but it is not yet clear whether these can be always recognized. It appears that monitoring of winds along an aircraft glide path in clear air or otherwise is feasible.

The extension of OB star winds to lower luminosities

view Abstract Citations (49) References (6) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The extension of OB star winds to lower luminosities. Snow, T. P., Jr. Abstract Mass loss rates for a number of early-to-mid-B main-sequence stars are compared with extrapolations of recently derived empirical correlations between M and stellar parameters for luminous OB stars. The order of magnitude of the rates for the B stars is consistent with a simple dependence on luminosity over the range from Of to mid-B, and is not consistent with previously derived correlations involving a dependence on mass or radius, which implies that luminosity is the dominant factor in driving the mass loss throughout the range of spectral types from mid-B main-sequence to Of. The winds in Be stars may represent a straightforward extension of the OB wind phenomenon to lower luminosities, and there appears to be no significant difference between B and Be stars in terms of their wind characteristics. Publication: The Astrophysical Journal Pub Date: February 1982 DOI: 10.1086/183732 Bibcode: 1982ApJ...253L..39S Keywords: B Stars; O Stars; Stellar Luminosity; Stellar Mass; Stellar Winds; Line Spectra; Oao 3; Silicon; Ultraviolet Spectra; Astrophysics full text sources ADS | data products SIMBAD (22)

IUE SPECTROSCOPY OF HOT BINARY STARS HD 108,HD 149404 AND HD 163181.

ABSTRACT High-dispersion IUE UV spectra of the hot binaries HD 108, HD 149404 and HD 163181 obtained at several orbital phases is presented in an attempt to assess the influence of the companion on stellar wind outflow. Spectra of HD 108, which has an extreme Of spectrum in the visible, show velocity changes over a range of 40 km/sec in the weak absorption lines, which, however, do not correlate with changes in the wind lines and do not support the binary nature of the object. The double-line O-type spectroscopic binary HD 149404 exhibits a stellar wind in the UV resonance lines which is not phase dependent. HD 163181 shows a clear phase dependence in its stellar wind, with wind phenomena strongest near periastron passage at phase 0.35 in the photometric ephemeris. An expanding Fe shell is indicated in all spectra, with expansion velocities lower than the main wind lines.

Vertical Structure of Yamase and Mountain Effect toward Yamase

The cool, moist easterly wind which blows over the eastern coast of the northern Japan during summer, is called “Yamase”. The Okhotsk anticyclone indicates the formation of the wind phenomena in this area. In addition, this wind also blows while traveling anticyclones cross over the northern part of Japan.The cool and moist Yamase Air Mass is distinguished from the other air masses. The air mass is characterized by easterly wind from the cool ocean surface, which is located in the north of Japan. The horizontal and vertical scales of the air masses are dependent on the types of the anticyclones. They are larger during the emergence of the Okhotsk anticyclone than under the traveling anticyclone. When Yamase blows, we can observe the great differnce of air temperature between the Pacific coast and the Japan Sea coast. The differnce is also greater during the emergence of Okhotsk anticyclone.The traveling anticyclone, passing over the northern part of Japan was investigated to identify the mountain effect on the mesoscale qualitative change of the Yamase Air Mass. The results are summarized as follows:(1) The depth of the Yamase Air Mass was about 500 meters, and a stable layer was identified above the air mass.(2) The Yamase Air Mass approaching with fog and low cloud was influenced by mountains. Consequently, less fog and low cloud with incresing solar radiation were observed between the windward and the leeward side of the mountains, if the elevations were between 400 and 500 meters above sea level.(3) The air temperature on the leeward side was very high in comparison with that of the windward side, and this phenomenon was seen only in a very thin layer (25 meters) near the ground.There was a sudden decrease in the air temperature between 400 and 525 meters, because of the horizontal advection of the Yamase Air Mass. The lower boundary of the inversion layer above 525 meters coincided with the upper boundary of the Yamase Air Mass.

Full-scale measurement of environmental wind in the shinjuku new metropolitan center

This study was an attempt to specify quantitatively the effects of tall buildings upon the properties of sorrounding winds. In the Shinjuku New Metropolitan Center in Tokyo, where six tall buildings each measuring∼200 m in height were located, cup anemometers were installed near the ground at 17 locations. Observations began in October 1975. Typical ground-level wind phenomena are illustrated in the results obtained from measurements made during two years. Moreover, wind-tunnel simulations corresponding to these full-scale measurements were also carried out. Comparisons of the velocity ratio, the deviation of wind direction and the gust factor between full-scale and wind-tunnel measurements are dealt with in this paper. Generally, the data resulting from both varieties of tests show marked correspondence.

Plasma fluid aspects of the solar wind

Significant progress in the description and understanding of the solar wind has been achieved with fluid models. Nevertheless, there is — so far — no general model capable of providing a mathematical solution for the overall solar wind phenomenon.

Stellar Mass Flux and Coronal Heating by Shock Waves

The heating of the solar corona and the solar wind phenomenon are basically related, however, the two parts are generally modelised independently: the models of the transition zone and corona are restricted to levels lower than the temperature maximum and the solar wind models begin above it. Here we study a self-consistent oversimplified model which maintains the global balance of energy sources and sinks from the chromospheric level to the interplanetary medium. The heating mechanism chosen is the shock wave dissipation; it was shown by Gonczi et al (1977) that overlapping shock waves could carry a significant mechanical energy flux towards a static corona; here we apply the same mechanism to an expanding corona. The model includes self-consistently the different coupling between convective energy flux, conductive flux, radiative losses in optically thin atmosphere, shock wave pressure and dissipation terms. The input parameters are the base pressure, the base temperature and the mechanical flux introduced at chromospheric level in form of shock waves. If these three parameters allow a solar wind expansion, the output results are the radial variations of the density, of the temperature, of the solar wind velocity and of the mechanical flux. Due to the presence of a boundary layer associated to the steep temperature gradient in the transition zone, the three input parameters cannot be arbitrarily fixed, in fact when we impose two of them, the third one cannot vary within a large interval (i.e. within a factor of two or less), this point has been qualitatively discussed in a previous paper : Couturier et al. (1979)

The estimation of extreme winds

The estimation of the magnitude of extreme winds, and of the risk of their being exceeded, is an essential part of the assessment of wind loads on structures. This paper surveys the various methods available for extreme value analysis which are directly applicable to wind data. These are of two types: those making use of a sampling procedure to derive the parameters of an extreme value distribution, and those which make estimates directly from the total or parent population of wind speeds. The former is a well established technique appropriate to the majority of applications, and will be described in greater detail. There is some disagreement among wind engineers as to the correct or most useful analytic form for the extreme value distribution of winds. In this paper it is argued that for temperate latitudes, where fully developed weather systems are the dominant cause of strong winds, the extreme value distribution is a Fisher-Tippett (Type I). There is a sound theoretical basis for the use of this distribution. In regions where there is a significant risk of strong winds originating from tropical cyclones and tornadoes a Fisher-Tippett (Type II) distribution may possess certain practical advantages, but a full solution of the problem of wind prediction in these areas should be based upon a different statistical approach, tailored to model these particular wind phenomena. This requires development and an accumulation of suitable meteorological data before it can be fully implemented. Brief mention is made of methods of estimating extreme winds from the parent population of wind speeds. This has application in cases where there is a very limited length of meteorological records, and also for the analysis of extremes on a directional basis where the more common methods are inapplicable. The paper is concerned with principles and does not include a detailed mathematical treatment of the topic, which should be south in the references.

Interdiffusion and intrinsic diffusion in binary vanadium-titanium solid solutions at 1350°C

Interdiffusion coefficients, intrinsic diffusion coefficients, and vacancy wind parameters have been determined in the vanadium-titanium system at 1350°C with the use of infinite, solid-solid diffusion couples. The experimentally determined diffusion coefficients were compared with the values predicted from the models of Darken, Manning and Dayananda with the use of available tracer diffusion and thermodynamic information and were found to be larger than those calculated from the three models. Vacancy wind parameters, determined experimentally, were seen to reflect a greater influence of the vacancy wind phenomenon on the intrinsic diffusion flux of each species than that calculated on the basis of Manning’s theory. In particular, the faster diffusing component is enhanced and the slower diffusing component is retarded to a greater degree than is theoretically predicted. Furthermore, experimental and predicted values of intrinsic diffusivity ratios,D V /D Ti ,were compared and the results suggest an increased effect of vacancy flow on the intrinsic fluxes with respect to the magnitude of this phenomenon calculated from Manning’s treatment. The vacancy wind effect is shown to be an important factor in the consideration of intrinsic diffusion fluxes and their relation to tracer diffusion and thermodynamic information in the vanadium-titanium system.

The magnetic ion‐mass spectrometer on Atmosphere Explorer

The magnetic ion‐mass spectrometer is designed to measure the abundances of the ambient positive ions in the ionosphere. It will be calibrated in flight against the retarding‐potential analyzer and the cylindrical electrostatic probe to give absolute concentration data for the ion species detected. These parameters can be measured to approximately ±10% in well‐behaved regions where concentrations are above 103 cm−3. However, in highly structured polar regions, some degradation in accuracy may be expected.Three mass ranges, covered simultaneously by the scan of the instrument, 1 to 4, 4 to 16, and 16 to 64 amu, permit measurement of the entire mass range, 1 to 64 amu, in 1 sec in the main (peaks) mode. An alternate mode, analog‐long, will extend the mass range to 90 amu with a 9‐sec period. Capability is provided to lock onto any set of mass numbers in the ratio 1:4:16 to give very high spatial resolution, e.g., 500, 250, and 125 m in the low‐, mid‐, and high‐mass ranges, respectively. This mode will be most useful in the despun satellite orientation to provide fine‐structure data on ion concentrations. In the spinning mode the phase shifts between roll modulation maxima of heavy and light ions determine the vertical component of the individual ion‐drift velocities. Values from a few km sec−1 to over 20 km sec−1 can be determined. Such data are applicable to the study of polar wind phenomena.

A statistical study of half-sibships born to parents affected with Huntington's disease.

<h3>Abstract</h3> Windstorms cause major disturbances in European forests and forest management can play a key role in making forests more persistent to disturbances. However, better information is needed to support decision making that effectively accounts for wind disturbances. Here we show how empirical probability models of wind damage, combined with existing spatial datasets, can be used to provide fine-scale spatial information about disturbance probability over large areas. First, we created stand-level damage probability models with predictors describing forest characteristics, recent forest management history and local wind, soil, site and climate conditions. We tested three different methods for creating the damage probability models - generalized linear models (GLM), generalized additive models (GAM) and boosted regression trees (BRT). Then, the damage probability maps were calculated by combining the models (GLM, GAM and BRT) with GIS data sets representing the model predictors. Finally, we demonstrated the predictive performance of the maps with a large, independent test data, which shows that the damage probability maps are able to identify vulnerable forests also in new wind damage events (AUC &gt; 0.7). Use of the more complex methods (GAM and BRT) was not found to improve the predictive performance of the map compared to GLM, and therefore we would suggest using the more simple GLM method that can be more easily interpreted. The map allows identification of vulnerable forest areas in high spatial resolution (16 × 16 m² raster resolution), making it useful in assessing the vulnerability of individual forest stands when making management decisions. The map is also a powerful tool for communicating disturbance risks to forest owners and managers and it has the potential to steer forest management practices to a more disturbance aware direction. Our study showed that in spite of the inherent stochasticity of the wind and damage phenomena at all spatial scales, it can be modelled with good accuracy across large spatial scales when existing ground and earth observation data sources are combined smartly. With improving data quality and availability, map-based risk assessments can be extended to other regions and other disturbance types.

Theoretical studies of the solar wind phenomenon

This paper is a review of current theoretical topics concerning the solar wind. Broadly speaking the questions outstanding at the present time concern the loss of angular momentum to the sun, the origin of the fluctuations observed in the wind at the orbit of earth, conditions in the wind in regions yet unvisited by spacecraft (inside the orbit of Venus, beyond the orbit of Mars, and out of the plane of the ecliptic), conditions at the terminus of the wind, etc. The question of angular momentum loss is important in understanding the evolution of the sun to its present form with a slowly rotating surface. Evidence from both comet and spacecraft observations of the wind indicate that the rate at which angular momentum is being carried away by the solar wind is very large, of the order of 1031 dyne/cm in the gas flow and half as much by the interplanetary magnetic field. But theory cannot account for more than about 1030 dynes/cm in the gas without special assumptions. The fluctuations presently observed in the wind at the orbit of earth have scales ranging upward from 102 km. Their presence is puzzling because fluctuations with scales less than about 106 km are not expected to survive from the sun. Presumably, therefore, the fluctuations are generated by the velocity differences of more than 100 km/sec in the wind from different regions in the solar corona and by instabilities produced by the anisotropy of the electrons of the wind plasma. Conditions in the wind at places far removed from the orbit of earth can be inferred from the behavior of cosmic rays. The evidence is that the wind becomes relatively placid beyond about 5 AU, extending from there out to 30–300 AU without much small-scale turbulence. There are also some suggestions that the wind may perhaps be less turbulent toward the sun from 1 AU, and that the wind may be faster and more turbulent at higher solar latitudes. But the ambiguity of the situation does not permit a firm conclusion on this yet.

The second wind phenomenon in McArdle's syndrome.

The second wind phenomenon in McArdle's syndrome.

A Discontinuity Surface Produced by Topographic Winds Over the Upper Snake River Plain, Idaho *

Eastern Idaho's Snake River Plain and that portion of the Continental Divide bordering it to the north comprise a topographic feature that provides an interesting local wind phenomenon. A sloping discontinuity surface is produced in a zone of conflict between slope ** and valley winds. The incursions of the front at the National Reactor Testing Station have become the subject of investigation because of their effect on the dispersion of stack effluents* Photographs are presented showing the effect of the frontal shear on a stack plume, smoke released at the ground, and a debris cloud from an experimental explosion. These photographs give an indication of the circulation pattern in the vicinity of the front. In addition, data from a network of recording stations, instruments on a 250-ft tower, and low-level wind and temperature soundings have been used to establish the circulation model. Information is presented to show seasonal and diurnal effects, and also the influence of major pressure systems on the front phenomenon.

Results of Meteorological Observations in the Five Years 1911–1915, also of Underground Temperatures in the Twelve Years 18981910 Made at the Radcliffe Observatory, Oxford

THE first part of this volume contains daily meteorological data, for the five years 1911 to 1915, in regard to barometric pressure, tempera ture, wind, cloud, sunshine, rain, ozone, weather notes, and occasional phenomena, according1 to a plan adopted in previous years. The figures re lating to wind are from two instruments of different dimensions, and a detailed comparison would be interesting, as the instruments are at very nearly the same height above ground, though not quite so nearly as the table makes them appear, since the higher one, given at 114 ft. in all the tables, is really at 116 ft. For this comparison, however, we must wait, as it cannot be made from the figures in the volume before us. Results of Meteorological Observations in the Five Years 19111915, also of Underground Temperatures in the Twelve Years 18981910. Made at the Radcliffe Observatory, Oxford. Vol. li. Pp. xv + 215. (Oxford: Humphrey Milford, 1916.) Price 15s. net.

Meteorological Report of the “Challenger” Expedition1

PREVIOUS to 1872, discussions of the fundamental problems of meteorology relating to diurnal changes in atmospheric pressure, temperature, humidity, wind, and other phenomena, may be regarded as restricted to observations made on land. It had then, however, become evident that data from observations made on land only, which occupies about a fourth part of the earth's surface, were quite inadequate to a right conception and explanation of meteorologieal phenomena; and hence, when the Challenger Expedition was fitted out, arrangements, were made for taking, during the cruise, hourly or two-hourly observations. These observations were published in detail in the “Narrative of the Cruise,” Vol. II. pp. 305-74, and are still by far the most complete yet made on the meteorology of the ocean.