bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical calculation of the displacements of a stratified airstream crossing a ridge of small height
Authors: Sawyer J. S. 
Published: February 2007

AbstractNumerical computations have been made of the solutions of the equation

which describes the stream lines in two‐dimensional flow of small amplitude in a stratified airstream. Solutions are computed for various variations of the parameter l as a function of height. (l2 = gβ/U2‐U−1∂2U/∂z2 is function of the wind and temperature variations with height in the airstream). To render the mathematical problem determinate the value of l2 is assumed to be constant above 16 km up to unlimited heights and by specifying the form of solution above 16 km consistent solutions are obtained for the troposphere little affected by the value of l2 assumed at high levels. The solutions include lee‐wave trains which diminish in amplitude downstream as well as those of constant amplitude. The method of solution results in the former appearing on the downstream side of the ridge only. (It is assumed that waves of constant amplitude can appear only on the downstream side).Some typical displacements of the stream lines are illustrated in Figs. 3 to 10. They are similar to those computed by Queney (1947) and Scorer (1949) but it is demonstrated that lee waves may arise from variations of l2 with height additional to those specified by these authors.
Drop‐size distributions from various types of rain
Authors: Mason B. J. , Andrews J. B. 
Published: February 2007

AbstractNotable differences are found in the size distribution of raindrops reaching the ground from frontal clouds exhibiting a radar melting‐band which is indicative of Bergeron‐type rain; from small, warm shower clouds in which the rain is formed by coalescence; and from thunderstorms. These differences are illustrated by typical drop‐size spectra and by plots of median‐volume drop diameter against rainfall intensity for the three classes.
A method of obtaining average bearing and incidence of rainfall
Authors: Rose C. W. , Farbrother H. G. 
Published: February 2007

AbstractThree tilted raingauges are symmetrically disposed round a vertical axis, with their collecting openings facing outward at an angle of 45° to the horizontal. From the ratios of the catches the mean direction of travel of a rainstorm can be estimated, and also the ratio of horizontal to vertical velocity of raindrops, provided it is less than unity. At Namulonge, Uganda (17 mi N of Kampala), between September 1954 and May 1956, the most common direction of rainfall was from the south, in the sector 150° to 210°, and the velocity ratio exceeded tan 10° for 90 per cent of the total rain.
Quasi‐periodic wind variations with height in the lower stratosphere
Authors: Sawyer J. S. 
Published: February 2007

AbstractQuasi‐periodic wind variations with height have been commonly observed in the lower stratosphere by means of the radar‐sonde theodolite at Crawley. The atmospheric disturbances which give rise to these wind variations have a vertical dimension of 1 km or so, but their horizontal dimensions must be much greater, perhaps of the order of several hundred kilometers. Perturbation theory is used to show that slow ‘inertia oscillations’ with a period of the order of half a day might have such dimensions.
Ice accretion and turbulence on North Atlantic air routes
Authors: Crossley A. F. 
Published: February 2007

AbstractRoutine observations made in transport aircraft in January and July, 1955–57, are analysed to obtain the frequency of ice accretion in relation to air temperature and of turbulence in relation to wind speed and cloud. Comparative freedom from icing in the range 0° to – 3°C is attributed to the effects of kinetic heating. In January the frequency attains a maximum of 43 per cent of occasions in cloud at – 4° to – 7°C; in July 20 per cent at – 4° to – 11°C. There is a secondary maximum in both months near the lowest temperatures at which icing is reported, which is attributed to flight through the upper parts of convection cloud. The frequency of icing in July is generally much less than at the same temperatures in January.Turbulence is reported on about 5 per cent of all occasions in January and on 2 per cent in July; in cloud the frequencies are 18 and 12 per cent respectively. The frequency of turbulence tends to increase with the wind speed.
Layer cloud over Southern England
Authors: Jones R. F. 
Published: February 2007

Abstract599 morning weather reconnaissance flights from the Royal Aircraft Establishment, Farnborough, over a period of approximately four years have been examined to determine the frequency of occurrence and thickness of layer cloud over Southern England. The chance of encountering 4/8 or more layer cloud in any kilometre height range decreased with height from about 1 in 2 near the surface to about 1 in 50 at a height of 12 km. Cloud layers when encountered were more likely to exceed one or two kilometres depth in the upper troposphere than in the lower but the frequency of encountering a layer more than 1/12 km deep was about 7 to 8 per cent at all heights. About 1 in 9 of all flights encountered cloud above the melting level more than 3 km thick. An examination of clouds in the temperature band 0 to – 15°C suggested that conditions suitable for severe clear ice formation on some aircraft might be encountered on about one per cent of flights. The same examination suggests that seeding of layer clouds by silver‐iodide smokes should produce some detectable modification of the cloud sheet on about 8 days a year.
The meteorological significance of remote measurements of infra‐red emission from atmospheric carbon dioxide
Authors: Houghton J. T. 
Published: February 2007

AbstractObservation from outside the atmosphere of the emission from different wavelength regions in the 15μ carbon‐dioxide band, would give information of the vertical temperature distribution between 10 and 50 km altitude. The measurements required are feasible using a Fabry‐Perot interferometer, and sample calculations of the depth in the atmosphere of the origin of this emission are presented.
An analysis of vertical wind‐fluctuations at heights between 500 and 5,000 ft
Authors: Smith F. B. 
Published: February 2007

AbstractA series of records, totalling over 120 hr showing the vertical fluctuations of high‐response wind‐vanes positioned on a captive balloon cable, are analysed to give statistical information on turbulence at heights between 500 and 5,000 ft, for an eddy frequency range 0·003‐12 cycles min−1. The use of specially designed filter and smoothing circuits facilitates the determination of the angular standard deviation of the inclination of the vane, as a function of run of wind, and of spectra, length‐scales and other parameters of turbulence. 18 spectra are given which show well‐defined peaks. Except in very stable conditions, the high wave‐number forms of the spectra are generally consistent with the existence of an inertial sub‐range. Estimates of the length‐scale, again excluding very stable conditions, do not apparently vary with height and average about 300 m. Intensity is found to depend on stability and to decrease in a very marked way with increasing wind speed, a result peculiar to these heights. This variation, applicable to specified meteorological conditions, is shown to have value in the determination of the spread of both continuous‐source plumes and clusters of particles according to recent treatments.
Calculations of the ascent of a saturated buoyant parcel with mixing
Authors: Mason B. J. , Emig R. 
Published: February 2007

AbstractNumerical computations are made to show how the vertical velocity, temperature, humidity‐mixing ratio and liquid‐water content of a cloudy parcel will vary with height and time as it ascends from the condensation level, rises through, and mixes with, the surrounding environment whose temperature and humidity distributions are specified. The rate at which the parcel is diluted by mixing is formulated in two different ways which lead to essentially the same conclusions. This treatment does not attempt a detailed description of the mixing processes but arrives at rather critical values for a single parameter used to represent the rate of mixing. If this is sufficiently large to prevent the vertical motion undergoing large oscillations (such as are experienced by a closed parcel), the first‐formed cloud is small ‐ usually only a few hundred metres deep over land and perhaps less than 100 m deep over the oceans. This implies that large clouds must evolve by successive thermals rising through air which has been warmed and moistened by their predecessors. Computations are made to demonstrate this stage‐by‐stage growth. The formation and growth of the first visible cloud appears to depend rather critically upon the excess temperature and velocity with which the thermal reaches the condensation level. These conclusions, and also the computed vertical profiles of temperature, updraught speed and liquid‐water in these small clouds, appear to be consistent with observations.
A simplified theory of the generation of sea breezes
Authors: Pearce R. P. 
Published: February 2007

AbstractThe equations of heating and motion are averaged vertically, assuming vertical distributions of velocity and temperature. A non‐linear partial differential equation of hyperbolic type is found to be satisfied by the surface velocity of the sea breeze. Numerical solutions are given for varying heating rates and for a superposed off‐shore wind. The method of integration of the equations leads to a spurious stable oscillation in the solutions and this is shown to be associated with the finite difference method used. Using dimensional analysis, a criterion for the prediction of the occurrence of sea breezes is suggested.
A smoke‐trail technique for measuring wind
Authors: Cooke T. H. 
Published: February 2007

AbstractIn the firing of low‐acceleration sounding rockets a knowledge of low‐altitude wind velocities before and during firing is necessary. Existing meteorological methods are inadequate, and the smoke‐trail technique here reported has been developed to augment these. The technique consists of visual or photographic analysis of the movement of a column of smoke and can be used to obtain the wind structure to heights up to about 1,500 ft.The present method of laying the smoke‐trail is by small solid‐fuel rockets, and suggestions are made for other methods which would reduce the cost of laying each trail. Possible uses of the smoke‐trail technique are considered.
Determination of stress from wind and temperature measurements
Authors: Panofsky H. A. 
Published: February 2007

AbstractAn integrated form of the diabatic wind profile based on similarity theory is used to estimate surface stress from measured winds and temperatures. It is shown that excellent estimates of stress can be made, given the roughness length, an estimate of the Richardson number and an accurate wind at one level. The theory can further be applied to estimate the roughness length from relatively few observations of wind and temperature not necessarily under neutral conditions.Suggestions by Taylor and Deacon for the determination of surface stress from autocovariance functions are tested on O'Neill observations. The results show that fair stress estimates can be made if instrumental response is taken into account.
The growth of large hail within a steady updraught
Authors: Browning K. A. 
Published: February 2007

AbstractAn analysis of the large‐scale organization of the Wokingham storm (Browning 1962b) shows that one of its constituent cells was particularly large and persistent. Throughout a 30‐min period, when it was most intense and producing the largest hail, this ‘Supercell’ exhibited a fairly steady structure which has been used to derive a model of the associated airflow (Browning and Ludlam 1962). In Part I of the present paper this model is given a quantitative basis. As a first approximation it is assumed that the airflow was two‐dimensional, but since the resulting model fails to account for the observed durations at the ground of hail and heavy rain it is modified to take into account a substantial convergent inflow towards the updraught from the right flank and towards the downdraught from the left flank. By applying and extending the analysis of hailstone growth within steady updraughts presented by Browning, Ludlam and Macklin (1963) and by relating it to the model of the airflow, it has been possible in Part II of this paper to account for the growth and the observed distribution of hail within the Wokingham storm. Two of the largest hailstones recovered are considered in detail because their structure can be explained only in terms of rather specific airflow characteristics. Their growth is shown to be consistent with the assumed vertical airspeeds within the updraught. Consideration of their growth‐times along with the distribution of hail at the ground suggests the presence within the updraught of horizontal components of motion relative to the storm of about 7 m sec−1 both towards its rear and towards its left flank. Finally, the existence is inferred of an abundant source of hailstone embryos owing to hailstones of all sizes re‐entering the foot of the updraught at levels above 4 km.
Bi‐annual variation of atmospheric ozone over the tropics
Authors: Ramanathan K. R. 
Published: February 2007

AbstractIt is shown that there is a bi‐annual variation of atmospheric ozone over equatorial, subtropical and lower middle latitude stations, a year of high ozone being followed by one of low ozone. A high ozone year in the sub‐tropics and lower middle latitudes corresponds to a year of low ozone near the equator. A possible connexion of this with the bi‐annual variation of zonal winds in the stratosphere of low latitudes is indicated.
The exponential wind profile
Authors: Swinbank W. C. 
Published: February 2007

AbstractFrom a definition and a hypothesis the form of the wind profile in the turbulent boundary layer when the air is thermally stratified is derived as magnified image.This solution is expected to be applicable in all stabilities and to all heights below which the shearing stress and the vertical heat flux remain constant.A critical examination of the experimental procedure necessary to test the validity of this, or of any, formulation for the steady‐state wind profile leads to a specification which the observational site and the weather conditions should meet.The results of a series of experiments are presented and analysed. These comprise measurements of wind speed and temperature at a number of levels up to 16 metres, supplemented by observations of net radiation, heat flux into the air and into the ground, and shearing stress. the analysis affords good verification of the form proposed for the wind profile.A variety of evidence is adduced to show that buoyancy modifies the transfer of heat more strongly than that of momentum, and that the discrimination increases with height above the surface.
Wind and temperature profiles near the ground in stable stratification
Authors: McVehil G. E. 
Published: February 2007

AbstractObserved wind and temperature profiles from O'Neill, Nebraska and Antarctica are analysed to determine their characteristics in inversion conditions. Analyses of the similarity between wind and temperature profiles are presented. These show that the profiles are generally similar when the Richardson number is small. However, there is strong evidence in the Antarctic data for a departure from similarity and a decrease in the ratio of eddy conductivity to eddy viscosity for Richardson numbers greater than 0·08.It is shown that the log‐linear wind profile fits the observations well for Richardson numbers less than about 0·14. the constant in the log‐linear equation is found to have a value of approximately seven in stable air, implying a critical gradient Richardson number of 1/7.From the log‐linear theory, heat flux and surface stress can be calculated given winds at two levels and the surface roughness. Predicted values are compared with observations. the agreement is good in the case of surface stress and fair for heat flux.
The equatorial tropospheric wind regime
Authors: Tucker G. B. 
Published: February 2007

AbstractWind observations in the troposphere above seven stations in the vicinity of the Equator have been analysed for the years 1961 and 1962. Strong mean meridional circulations emerge as features of the tropospheric wind regime. Easterly winds occur throughout most of the troposphere, but at times during the northern hemisphere winter a net westerly wind appears to exist in the upper troposphere. There is a strong momentum flux towards the summer hemisphere; the greatest contribution to this comes from the standing eddy flux which is due largely to strong monsoon influences on the flow patterns at 200 mb and above in the Indian Ocean‐West Pacific sector.
The flux‐gradient relation for turbulent heat transfer in the lower atmosphere
Authors: Dyer A. J. 
Published: February 2007

AbstractData obtained during February and December 1962 at a carefully‐chosen micrometeorological site at Kerang in Northern Victoria are used to examine the flux‐gradient relation for sensible heat transfer. The analysis is carried out for 70 half‐hour runs specially selected for steady state lapse conditions to determine the variation with the stability parameter, z/L, of the Monin‐Obukhov ‘universal function,’ øH.In the range 0.02 < |z/L| < 0.6 it is found that the value of the index ϵ in øH α |z/L|ϵ is − 0.33 ± 0.02 in excellent agreement with the ‘free convection’ regime of Priestley and the −4/3 power form of the temperature profile. The corresponding value of H* is 1.32 ± 0.06.For |z/L| > 1, ϵ is found to be −0.38 ± 0.10 in contrast to Townsend's suggestion of −1 for this region based on laboratory evidence. Regression analysis for the region |z/L| > 0.2 yields a value of ϵ of −0.50 ± 0.02. The suggestion is offered that the motions observed by Townsend may occur in the atmosphere but as transient phenomena in which the applicability of the conventional similarity principles is to be questioned.The formula H = 24Δθ3/2 based on Priestley's regime with sensible heat H in mw cm−‐2, and potential temperature difference Δθ between 1 and 4 metres in ° provides a practical basis for the evaluation of the heat flux from profile measurements.
The effect of wind shear and vertical diffusion on horizontal dispersion
Authors: Tyldesley J. B. , Wallington C. E. 
Published: February 2007

AbstractFeatures of analytical solutions of atmospheric diffusion equations show that the effect of wind shear and vertical diffusion on horizontal dispersion is important at great distances. Methods of using an analogue or a digital computer to solve the equations for all but very short distances are described. Computations indicate that the wind shear effect is probably dominant over a wide range, and these indications are confirmed by reference to broad and specific deductions from experimental data.
Some aspects of convection as measured from aircraft
Authors: Grant D. R. 
Published: February 2007

AbstractTemperature and humidity fluctuations obtained from a fast‐responding thermometer and radio refractometer in convective conditions over a flat surface have been studied. Warm, moist ascending patches of air emerging from a layer of mechanical turbulence near the surface were observed up to about 600 m. The excess temperature of these patches decreased rapidly with height. Between 1,000 m and cloud base (1,300 m) there was evidence of warm dry air descending from above cloud base. This could make a significant contribution to the warming in the convective layer.
Estimating the longitudinal wind spectrum near the ground
Authors: Berman S. 
Published: February 2007

AbstractA graphical procedure for estimating the spectrum of the longitudinal wind component from height, mean wind speed, roughness length, and stability data is presented, based on observed spectra at many locations.Using non‐dimensional coordinates following Monin, the amplitude of the spectrum peak in neutral stability shows no systematic variation with height, while the corresponding dimensionless frequency varies with height to the 0.75 power. At relatively high frequencies, spectra observed in unstable conditions are indistinguishable from those in neutral stratification. At lower frequencies the ratio of the spectrum in highly unstable conditions to that in the neutral case approaches 3 : 1 at low heights and decreases to less than one in stable air.
Estimation of insolation for West Africa
Authors: Davies J. A. 
Published: February 2007

AbstractCoefficients are determined for regressions of insolation upon sunshine using data from six West African stations. The analysis, using total, station and monthly data groupings, indicates high correlation (r = 0.86 to 0.99) for monthly groupings. A pronounced annual cycle and range in the coefficients (a = −0.12 to 0.26, b = 0.50 to 0.99), are explained in terms of variations in cloud cover and atmospheric turbidity. A turbidity index ‘t,’ has values similar to those obtained in East Africa.
Vertical profiles of total precipitation in shower situations
Authors: Hamilton P. M. 
Published: February 2007

AbstractVertical profiles of the total precipitation in the area scanned by a radar have been obtained for the first time. Profiles in shower situations show that precipitation commonly accumulates at an upper level. In the more severe storms the accumulations persist for an hour or more, descending slowly during this time. There is evidence that the storms dissipate quickly with a marked increase in severity as the accumulation reaches the melting level.Observations have shown that the height at which the accumulation forms steadily increases with the available energy of convection. Theoretical work by East (1957) and Kessler (1961) predicts an accumulation at a height that increases with the updraught speed. A combination of these two approaches has led to relations among the three quantities: energy of convection, updraught speed and height of accumulation. The value of these relations in the analysis of convective storms is demonstrated by using them to interpret the behaviour of a particular severe storm.
The vertical distribution of atmospheric ozone and possible transport mechanisms in the stratosphere of the Southern Hemisphere
Authors: Kulkarni R. N. 
Published: February 2007

AbstractAn analysis of the small‐scale fluctuations in the vertical distribution of ozone calculated from Umkehr observations at Brisbane (27°.5S, 153°.0E) and Aspendale (38°.0S, 145°.1E) shows that these fluctuations extend up to about 30 km in late summer and early autumn and only up to about 24 km in late winter and early spring. Ozone content in the troposphere and lower stratosphere increases with increasing total ozone.Mean meridional distributions of ozone with height have been constructed for the Southern Hemisphere for summer and spring and the results are discussed in relation to the idea of meridional poleward and downward flow of air from the upper part of the tropical troposphere and lower stratosphere. It appears that the changes in the spring amounts of ozone from year to year take place essentially in the 24 to 36 km layer in the middle latitudes of the Southern Hemisphere. Also, above about 25 km, the ozone amount is smaller at 65°S with greater amounts on either side of it. To explain this a transport mechanism above 25 km, consistent with isentropes above that level, is suggested.
Some aspects of the theory of fronts and frontal analysis
Authors: Kirk T. H. 
Published: February 2007

AbstractFronts are considered as aspects of development and it is shown that their characteristics can be deduced without recourse to the traditional concept of air masses. The approach interprets the current practice of synoptic analysis in terms of dynamical theory and, as a corollary, affords the possibility of utilising automatic computational methods for the objective depiction of frontal zones and their associated weather.