bluuebunny/crossref_metadata_2025_split huggingface dataset:
A report on some experiments in numerical prediction using a stream function
Authors: Knighting E. , Hinds Mavis K. 
Published: February 2007

AbstractA series of experiments is described in numerical forecasting in which the wind field at mid‐tropospheric level is derived from a stream function, but the wind shear in the lower troposphere is computed in a variety of ways. The results show that the overestimation of the pressures in the region of anticyclones, which is inherent in models in which the mid‐tropospheric wind field is assumed to be geostrophic, is significantly reduced.
Some aircraft observations of fluxes of solar radiation in the atmosphere
Authors: Roach W. T. 
Published: February 2007

AbstractAn account is given of some recent observations of solar‐radiation fluxes from aircraft of the Meteorological Research Flight. This account consists of two parts:
High‐level measurements of the albedo of the earth and atmosphere from a Canberra aircraft over southern England in 1958 and 1959, and over the Sahara Desert and Equatorial East Africa in June 1958 and January 1960.
Observations from a Hastings aircraft of the absorption and reflection of total and visible solar radiation from a cloud‐free atmosphere over the English Channel.
From (1), frequency distributions of observations within given albedo ranges have been extracted and correlation of albedo with the observed cloud cover attempted. The mean of albedo observations over southern England was 0·5 in 1958 and 0·3 in 1959; over the Sahara Desert about 0·3 and over Equatorial Africa about 0·2.The Hastings flights show that instantaneous heating rates in excess of 5°C/day at some level below 10,000 ft occur quite frequently. When allowance is made for heating due to absorption by the near infra‐red bands of water vapour and carbon dioxide (1‐2°C/day) it is found that the residual absorption does not depart significantly from greyness except in a few cases when the absorption appears to be concentrated in the near infra‐red.For the lowest levels, the absorption coefficient due to haze for total radiation is estimated to average about 20 per cent and for visible radiation about 5 per cent of the attenuation coefficient. Back‐scattered radiation accounts for about 5 per cent of the total attenuation.
A three‐parameter model of the atmosphere suitable for numerical integration
Authors: Bushby F. H. , Whitelam Clare J. 
Published: February 2007

AbstractSubject to various approximations, a system of five simultaneous equations (three partial differential equations and two algebraic equations) is derived to predict the height of three contour surfaces corresponding to the bottom, middle and top of the troposphere and to evaluate the two fields of vertical motion corresponding to the upper and lower halves of the troposphere. The atmospheric model used is an extension of the two‐parameter model proposed by Sawyer and Bushby (1953).Numerical integrations have been carried out for 20 cases and the results are given in statistical form. Two forecasts are illustrated with diagrams. The accuracy is better than that obtained with the two‐parameter model, and the forecasts are of the same standard as those produced by conventional methods.
A graphical method of objective forecasting derived by statistical techniques
Authors: Freeman M. H. 
Published: February 2007

AbstractThe objective forecasting technique described consists of a composite diagram from which the forecast value of the predictand can be read directly, given the values of the predictors. Each section of the diagram combines a new predictor with an estimate of the predictand obtained from the previous sections. The isopleths in the diagrams are obtained by fitting a curved surface (involving powers and cross‐product terms of up to the fifth order) to the basic data by a ‘least squares’ procedure. Only terms which are significant at the 5 per cent level are retained in the regression formulae so produced. At each stage the predictor to be selected is that which contributes most to the combination so far chosen.The method was used to forecast visibility (as one of 32 code figures) at London Airport three and six hours ahead. When it was tested on two winters' independent data, correlation coefficients of 0·89 and 0·83 were obtained for the 3‐hr and 6‐hr forecasts, respectively. During the same period the figures for the normal subjective forecasts made at London Airport were 0·87 and 0·74.
Fitting meteorological extremes by various distributions
Authors: Gringorten I. I. 
Published: February 2007

AbstractMeteorologists often fit extreme values by the double‐exponential distribution, the limiting form of distributions of the exponential type. But distributions of some extremes, such as the lowest annual temperatures (1875–1960) at Washington, D.C., fall well short of the limiting form. Alternative means of fitting sets of extreme values are proposed. For data such as the highest January temperature at Washington, an extra physical phenomenon appears to restrict the magnitude of the largest values.
Radiative flux divergence in radiation fog
Authors: Funk J. P. 
Published: February 2007

AbstractRadiative flux divergence (div R) recordings at heights between 1 and 11 m have been carried out before and in the initial stages of radiation fog. Temperatures, temperature gradients, radiation ground temperature, net radiation, relative humidity and wind speed were also measured.The general pattern showed essentially either a high div R preceding fog formation (once short‐lived radiative cooling of over 30°C hr−1 was observed); or a high div R some time before, interrupted by a period of very reduced, or even negative div R (radiative warming), with resumed radiative cooling only immediately before fog formation.It is reasoned that radiation and, to some degree, temperature phenomena during fog formation can be patchy in character and that some of the results observed on different occasions may actually happen on one and the same occasion. These and other indications suggest small‐scale advection to be important.The results also demonstrate the important role of haze and suggest its vertical distribution rather than quantity to be the important factor.The div R observations show the driving character of radiation and can readily explain the dissipation of latent heat of condensation and many observational facts which were difficult to interpret by conventional reasoning, such as the absence of fog under seemingly ideal conditions or the suddenness of its onset. A composite picture of radiation fog formation is given.
The effect of wind shear on horizontal spread from an instantaneous ground source
Authors: Saffman P. G. 
Published: February 2007

AbstractThe medium range spread of a cloud of material released in a turbulent wind is considered theoretically. Attention is directed to the effect of systematic wind shear with height to see whether this may be important. It is shown that there are two cases, according to whether the height to which the material may rise is effectively bounded or not.In the first case when the height is bounded, the situation is in essentials the same as for flow in a pipe (Taylor 1953, 1954). After a sufficient length of time, the horizontal spread is described by a diffusivity which is the linear sum of two components, one representing the effect of horizontal turbulent fluctuations of the wind, and the other the effect of an interaction between the systematic wind shear and the vertical transport of material by the turbulence. For given mean wind profile, the latter effect is proportional in an inverse way to the coefficient of vertical diffusion.In the second case, when the material may rise to any height, it is shown that the horizontal spread cannot be described, in general, by a constant diffusivity, and that the horizontal mean‐square spread or dispersion does not increase linearly with the time. However, the horizontal fluctuations and the interaction of wind shear with vertical transport still contribute independently to the horizontal dispersion. It is found that the interaction effect now depends in a direct way on the coefficient of vertical diffusion. It is also concluded that for medium‐range diffusion the effect of the interaction of wind shear with vertical transport is dominant.
Electrification accompanying melting of ice and snow
Authors: Matthews J. B. , Mason B. J. 
Published: February 2007

AbstractAttempts to measure the electrification produced by the melting of ice and snow, known as the Dinger‐Gunn effect, have been made with three different experimental arrangements. In one of these snow crystals were grown and melted under very clean conditions inside a diffusion cloud chamber. The results of the three experiments are consistent in failing to detect a separation of charge and in indicating that any charge produced was < 10−2 e.s.u./g or two orders of magnitude smaller than reported by Dinger and Gunn. This result was unaffected by varying the purity of the ice, its air content and the rates of freezing and melting, and the pH value of the water. Accordingly, it is concluded that charging associated with the melting of snow or hail is unlikely to be an important feature in the electrification of clouds and precipitation.
The influence of cloud on hourly amounts of total solar radiation at the sea surface
Authors: Lumb F. E. 
Published: February 2007

AbstractEmpirical relations are found for the hourly short‐wave radiation Q received on a horizontal surface at ocean weather station Juliett (52° 30'N, 20°W), for nine categories of cloud, in the form Q = 135 fs (mw hr cm−2) where f = a + b s is the fraction of solar radiation transmitted through the atmosphere, s is the mean of the sines of the solar altitude at the beginning and end of the hour, and a, b are constants.A comparison with a similar analysis of radiation data at station Alfa indicates that the relationships derived for Juliett are valid over a wide band of latitude, and it is shown that they can be used to estimate (within ϕ 10 per cent on most occasions) the total solar radiation received at the sea surface during 5‐day periods over the North Atlantic between 45° and 65°N.
The influence of impact velocity and ice specimen geometry on the charge transfer associated with temperature gradients in ice
Authors: Latham J. , Stow C. D. 
Published: February 2007

AbstractWhen pure uniform ice specimens of different temperatures are brought into gentle contact for times ranging from 10−3 to 5.10−2 sec and are then separated, the charge transfer is a maximum for a contact time of about 7.5 × 10−3 sec and is in agreement with the equations of Latham and Mason (1961a). With ice of higher conductivity the maximum charge transfer occurs after smaller contact times.For impact velocities less than about 7.5 cm sec−1 the charge transfer is in agreement with the theory but above this value the charge transfer increases linearly with impact velocity. The charge transfer is also enhanced, by as much as an order of magnitude, if the ice specimens are tapered. A tentative conclusion to be drawn from these experiments is that the value of 5 × 10−4 e.s.u., measured by Reynolds, Brook and Gourley (1957) for the charge transfer per collision between an ice crystal and a warmer artificial hailstone, which is sufficient to generate charge at a rate required by a tenable theory of thunderstorm electrification, may be explicable in terms of the temperature‐gradient effect.When steady temperature gradients are applied to uniform specimens of pure ice the potentials developed across the ice are unaffected by the pressure to which the ice is subjected. The application of steady temperature gradients to tapered ice specimens produces potentials which are up to an order of magnitude greater than predicted theoretically.
The lobe structure of giant hailstones
Authors: Browning K. A. 
Published: February 2007

AbstractPhotographs of thin sections through five giant hailstones are presented to portray their bubble and crystal structures. These are interpreted to show that the hailstones grew as three‐dimensional arrays of more or less completely frozen lobes, sometimes but not always separated by regions of spongy ice characterized by radial lines of bubbles.Some lobes contained regularly spaced hyperfine growth layers consisting of series of concentric bubble fronts a few hundred microns apart. These layers are interpreted as being due to fluctuations in growth rate associated with the tumbling of the hailstones.The growing surfaces of the lobes were strongly convex outward. This caused successive growth layers to become convoluted or scalloped. When the surface of a whole hailstone was viewed it sometimes created the false impression that the stone was an aggregate of much smaller hailstones.The presence of surface knobs associated with the lobes significantly enhances the efficiency of heat loss from the hailstone surface. Such an effect is important in that it reduces the proportion of unfrozen water incorporated within a rapidly growing hailstone. There is even some evidence that a giant 8 cm diameter hailstone can grow in this way without becoming appreciably spongy.
A pilot study of small‐scale wind variations in the stratosphere and mesosphere
Authors: Newell R. E. , Mahoney J. R. , Lenhard R. W. 
Published: February 2007

AbstractA series of high resolution robin falling‐sphere soundings covering the altitude range from 70 to 27 km have been examined in detail. Small‐scale wind variations with height are evident throughout. From profiles of the zonal wind components the apparent amplitudes and half‐wavelengths have been tabulated and summarized for 19 cases, divided into two seasons. A data‐reduction technique which imposes variable smoothing upon the initial balloon‐position data complicates the analysis, but the existence of wind fluctuations with vertical half‐wavelengths between 300 in and a few kilometres is definitely established.A linear theory which takes into account the effects of rotation and temperature lapse rate upon such motions is briefly discussed. It is shown that the vertical flux of energy associated with the motions may be an important energy source for the atmosphere above about 80 km. A firm estimate of the magnitude of the vertical energy flux requires further information about the periods and/or the horizontal scales of the observed motions.
A note on some measurements from aircraft of precipitation within frontal clouds
Authors: Cornford S. G. 
Published: February 2007

AbstractFlights have been made within frontal clouds over southern England to investigate the distribution of precipitation in the horizontal and the vertical through the systems. Several examples are presented. It was found that there is a large variability both in time and place on all scales which makes it difficult to produce a general description. In all cases the contribution to the total rain amount from the cloud layers well above the freezing level was small and the majority came from the lowest levels. In one case all the frontal precipitation was produced in the liquid phase. Some surprisingly high values of precipitation rate were found near cloud base and have not yet been explained.
The lapse rate of temperature following an air parcel
Authors: Staley D. O. 
Published: February 2007

AbstractThe lapse rate of temperature following an individual air parcel is derived assuming continuity of temperature, density, motion, and non‐vertical ascent in a changing pressure field. The result differs substantially in form and sometimes in magnitude from that obtained by the usual theory in which the ascent is strictly vertical and the parcel is discontinuous. When non‐vertical ascent and continuous fields are taken into account, important terms arise when the pressure field varies rapidly with time or along the horizontal coordinates. The importance of the departure of the unsaturated parcel lapse rate from gc in the computation of vertical motion by the adiabatic method is noted.
On the interhemispheric mass circulation across the Equator
Authors: Palmén E. 
Published: February 2007

AbstractThe discrepancy between some recent computations of the mean meridional mass circulation across the Equator is discussed. It is shown that the most probable toroidal mass circulation across the Equator amounts to about 120.1012 g sec−1 in winter (December‐February) and to about 180.1012 g sec−1 in summer (June‐August). In winter the circulation at low altitudes is southward and in summer, northward.
Turbulent energy dissipation rates and exchange processes above a non‐homogeneous surface
Authors: Record F. A. , Cramer H. E. 
Published: February 2007

AbstractEnergy dissipation rates and the eddy fluxes of sensible heat, momentum, and total kinetic energy have been measured above a non‐homogeneous surface. Calculations were made from simultaneous observations of fluctuations in air temperature and the orthogonal components of wind velocity at heights of 16 m and 40 m. In all thermal stratifications, dissipation rates given by the Kolmogoroff structure function are in close agreement with direct measurements of the energy extracted from the mean flow. During stable stratification, energy losses due to work done against gravity and to the divergence of the vertical flux of turbulent kinetic energy are nearly an order of magnitude smaller than the dissipation. In unstable stratification, energy losses due to the flux divergence are of the same order as the dissipation and are approximately three times larger than the energy produced by buoyancy. Estimates of the vertical heat flux from the Obukhov structure function compare favourably with directly‐measured fluxes if the constant in the structure function is assigned a value of 0.7 in lapse conditions and a value of 1.6 in inversion conditions. The measurements also show that the ratio of the diffusivities of heat and momentum at a height of 16 m is significantly greater than unity in unstable stratification and significantly less than unity in stable stratification. Finally, the new measurements of dissipation rate are shown to be consistent with values obtained in previous studies.
Some measurements of turbulence in altocumulus clouds
Authors: Watson N. R. 
Published: February 2007

AbstractThe method used to measure vertical gust components from aircraft and the instrumentation for this work installed in the Canberra aircraft of the Meteorological Research Flight are described. Sections showing the vertical gust components obtained during penetrations of altocumulus cloud are presented. Root mean square values were found to be about 0·5 m sec−1 in the middle of the cloud. There appeared to be some damping of the turbulence in the top of the cloud when it was under an inversion.
Some aspects of the accretion process
Authors: Macklin W. C. , Payne G. S. 
Published: February 2007

AbstractThree aspects of the ice accretion process are considered. Firstly it is shown experimentally that, as the deposit temperature is raised, the individual droplets pack more closely giving a more compact and denser deposit. Models of the freezing process are then proposed and the freezing times of the droplets calculated theoretically. These calculations show that even with low density rime deposits the deposit temperature is the prime factor in governing the freezing. Finally, the statistical nature of the accretion process is considered and the probabilities of one or more droplets arriving and interfering with the freezing and cooling of an initial droplet are deduced.
Electrification accompanying the melting of ice particles
Authors: Drake J. C. 
Published: February 2007

AbstractIt was observed that during the melting of small ice particles supported in a vertical wind tunnel, strong convection currents developed in the melt water. Bubbles released from the ice during melting were swept up by the currents and rapidly transferred to the surface where they burst. The separation of electric charge accompanying the bursting of the bubbles was highly dependent on the convection currents in the water. The observed charging effects are not entirely consistent with theories based on the disruption of an electric double layer. In particular, the separation of charge is considerably increased if the air contains high concentrations of CO2. It is shown that the observed values of charge separation are sufficient to account completely for the presence of the lower pocket of positive charge found below the melting level in many thunderstorms.
A theoretical study of cup and vane anemometers
Authors: Ramachandran S. 
Published: February 2007

AbstractThe predictions of a simplified theory of anemometers are compared with observation.The theoretical response of cup and vane anemometers to steady and varying flows are derived analytically and by using an analogue computer.It is found that the mean indicated windspeed can be overestimated by as much as 20 per cent and that the form of fluctuations is distorted and their amplitude considerably reduced.
An experiment in numerical prediction in equatorial latitudes
Authors: Krishnamurti T. N. 
Published: February 2007

AbstractA short‐range prediction experiment is performed to study the dynamical structure of the tropical atmosphere in equatorial latitudes. The initial field includes the intertropical convergence zone and associated disturbances over the western Pacific Ocean during March 1965. A complete initial state is constructed using a consistent balanced system of equations. The procedure involves construction of pressure, temperature and vertical motion distributions starting from the rotational part of the observed wind field. It is shown that this procedure, the validity of which assumes a small Rossby number, does not yield a realistic field of vertical motion.A short‐range prediction with a multi‐level prediction model yields some interesting solutions in the vicinity of the intertropical convergence zone. During the first 18 hours of prediction there occurs an adjustment of the motion and the mass field, with gravity‐inertia oscillations.An important feature of the model is a parameterization of cumulus convection as a function of the largescale moisture convergence. The role of cumulus scale heating in the vicinity of the intertropical convergence zone is investigated and it is shown that during the adjustment process a convergence zone forms which exhibits a strong coupling with the zone of frictional vertical rising motion and the field of computed cloud cover. The formation of this feature appears to represent the numerical simulation of a tropical storm.
The energy formula in a moving reference frame
Authors: Betts A. K. , McIlveen J. F. R. 
Published: February 2007

AbstractThe energy formula quoted by Green, Ludlam and McIlveen (1966) requires an additional term if it refers to a frame moving over the Earth's surface. The correction is derived for steady motion of the frame and tested observationally. The error incurred by ignoring the motion of a weather system is discussed.