bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forecasting the summer weather of the sudan and the rains that lead to the nile floods
Authors: El‐Fandy M. G 
Published: February 2007

AbstractIn the Sudan, pressure‐distribution shows a characteristic seasonal variation. In summer (mainly June to August) a trough of low pressure (of the belt of the thermal equator) covers the Northern Sudan. An oscillatory barometric minimum is located over the NE. Sudan and is normally an area of almost cloudless skies and intense insolation; while over the greater part of Abyssinia and the SE. Sudan extends a barometric maximum (of the Indian Ocean anticyclone) which also suffers fluctuations in its strength and northward extent. “Haboobs” and local convectional rain over the Sudan usually accompany the northward oscillations of this barometric maximum. It is in tracing such oscillations of the main pressure systems that pressure becomes of some value in forecasting weather in these low latitudes.The present paper is devoted to a study of the disturbances in the average pressure distribution and the variations in the general wind circulation which are associated with the day‐to‐day outstanding changes of the weather of the Sudan. Four different types of summer disturbance have been distinguished as follows:—(1) Sand‐storms, or “haboobs”, with a modification of the general circulation by the onset of strong S. winds. These storms are common over the desert areas of the central and northern Sudan. Marked strengthening (and deepening) of the S. to SW. monsoon usually accompanies the northward extension of the barometric maximum of the SE. Sudan together with a northward oscillation of the intertropical convergence zone (I.C.Z.). The origin of this modification of the general circulation appears to lie in a pressure surge which first shows itself by a rise of pressure and fall of temperature in the S. Sudan‐Uganda area and spreads northwards rapidly.(2) Dust‐storms, or “haboobs”, with “induced cold fronts”, or line squalls set up by thunderstorms.(3) Low‐level (or local instability) thunderstorms, which form, under favourable conditions of temperature and humidity, by direct convection within the S. to SW. monsoon. These generally occur when the I.C.Z. is at its farthest north, the depth of the monsoon current being then greatest and there is marked increase of moisture content within the lowest layers.(4) High‐level (or widespread) thunderstorms followed by fairly widespread outbreaks of rain. The term “wide‐spread rain” has been proposed to describe the rainfalls which cover a wide area and may persist for about 24 hours in places.
A note on the eddy transport of angular momentum
Authors: Starr Victor P. , Sheppard P. A. 
Published: February 2007

AbstractA pilot study of the horizontal eddy transport of angular momentum in the meridional direction, based on radio wind observations over the North American sector of the northern hemisphere, is presented. The results are in harmony with general frictional requirements except that the transports are rather large. The desirability of much more extensive compilations of data concerning the subject is indicated.
The vertical convective heat flux in the atmosphere—a critical essay
Authors: Robinson G. D. 
Published: February 2007

AbstractA definition of convective vertical heat flux is proposed which leads directly to the expression p1 w1 h1 where p1, w1, and h1 are, respectively, simultaneous values of the fluctuating density, vertical velocity relative to the surface, and total heat per unit mass at a point in a constant pressure surface. Neglect (apparently justifiable) of the pressure fluctuations yields the expression cpp±w1/R for the convective flux of sensible heat. The distinction between free and forced convection is made. Recent treatments by Montgomery and by Priestley and Swinbank are examined with particular attention to the importance of free convection. It is submitted that neither Montgomery's neglect of the buoyancy forces nor Priestley and Swinbank's arguments suggesting their universal importance can at present be justified. In particular the latter authors explanation of the normal tropospheric lapse rate is questioned.
On the stability of stably stratified shearing layers
Authors: Scorer R. S. 
Published: February 2007

AbstractThe equation governing the behaviour of two‐dimensional waves in a horizontal stably stratified shearing air current is set up. It is shown that it may be obtained by considering the limit as the number of a set of superposed statically‐neutral layers, each of constant stream velocity, tends to infinity, but that the properties may differ considerably if the number of layers is few.If stable waves occur then at no level do they travel with the same velocity as the air. If unstable waves occur the surfaces containing the wave crests may be so inclined to the vertical as to limit the growth of the waves. Some remarks are made concerning the difficulties of discussion of unstable waves in the general case.
The electric charges and masses of single raindrops
Authors: Hutchinson W. C. A. , Chalmers J. Alan 
Published: February 2007

AbstractRaindrops were admitted by a cone‐shaped opening into an insulated vessel connected to a valve amplifier for measuring the drop charge Q. Drop radius a was found by the absorbent paper method. The field at the ground and the point discharge current I were also measured. Most often, but not always, the signs of the drop charge and field were opposite. During point discharge, 173 drop charges and masses were measured, and statistical analysis showed a definite correlation between Q and I—, a probable correlation between Q/—I and a and a possible correlation between a and —Q. By grouping drops according to radius, and taking averages within the groups, the approximate relationship Q/—I ∞ a was obtained. In one period when the radius was nearly constant, the observations gave the connection Q ∞ — I without taking averages. The observed relation between Q and I corresponds to the results of Simpson (1949) for the charge on a volume of rain. The observed charges were mostly much higher than predicted on Wilson's ion‐capture theory, unless the field increases considerably with height in the atmosphere.
The diurnal march of vapour pressure on sea‐breeze days at Athens, Greece
Authors: Karapiperis Ph. 
Published: February 2007

AbstractThis study is restricted to days with even pressure distribution, and without strong winds that would interfere with the sea breeze. The greatest frequency of such a sea breeze occurs in May, June and October, which are the months of low frequency of the Etesians.The diurnal march of vapour pressure at Athens is clearly double in all months and the year as a whole. However, on days with uninterrupted sea breeze, mainly from May to October, three pairs of extremes characterize the variation, there being two secondary maxima and two secondary minima in the forenoon. The arrival of the moist sea breeze overcompensates the normal decrease of vapour pressure in the morning.
Sequences of wet and of dry days considered in relation to the logarithmic series
Authors: Williams C. B. 
Published: February 2007

AbstractIt is shown that the frequency distribution of sequences of fine days conforms very closely to a ‘logarithmic’ series. The sequences of ‘wet’ days do not conform so closely, as there is a shortage of one‐day sequences and an excess of 2 to 4‐day sequences, but this may be due to the method of defining ‘wet’ sequences.
Further computations of 24‐hr pressure changes based on a two‐parameter model
Authors: Bushby F. H. , Hinds Mavis K. 
Published: February 2007

AbstractThe results of 13 computed 24‐hr forecasts, using the Sawyer‐Bushby (1953) two‐parameter model atmosphere, are discussed, and further computations to investigate the apparent limitations of the model are described. The effects of the neglect of heating of the atmosphere over the sea, of the use of incorrect boundary conditions and of the use of 500‐mb rather than 600‐mb data are investigated. It is concluded that the imposition of artificial boundary conditions can cause considerable errors, although these will not be serious in the region of the British Isles, and that the effects of non‐adiabatic heating of the air over the sea should be included in the computations.
Geostrophic and ageostrophic wind analysis
Authors: Smith F. B. 
Published: February 2007

AbstractAerological data for the British Isles, 1953, at nine pressure levels, are analysed, to give the geostrophic and ageostrophic components of the wind and the radius of curvature of the isobars. The mean total energy over unit surface area is found to be 1·71 × 109 erg cm−2.The equation of energy associated with the ageostrophic component is obtained, and the work done by the flow down the pressure gradient is identified by means of this equation with a Coriolis term and a centrifugal term. These are estimated from the data, giving a value for the rate of generation of kinetic energy of 8·8 × 103 erg cm−2 sec−1. The mean net mass‐flux across unit length of isobar is found to be 25 kg cm−1 sec−1. The order of magnitude of this quantity is checked in the final section in which a mathematical analysis is applied to a model depression filling by the influx of mass across its perimeter.
The influence of the 9.6 micron ozone band on the atmospheric infra‐red cooling rate
Authors: Plass G. N. 
Published: February 2007

AbstractThe upward and downward radiation flux and the heating and cooling rate in the atmosphere have been determined for the 9.6 μ band of ozone from the absorption measurements of Summerfield. Three different ozone distribution curves as well as three different temperature‐height curves have been used for these calculations. The radiations that interact with the 9.6 μ ozone band always act to cool the atmosphere from the earth's surface to a height of several kilometres and to heat the region from there to approximately 20 km. The heating or cooling rate is never larger than a few tenths of a degree Celsius per day in this region. On the other hand, from 35 to 60 km the usual order of magnitude of the cooling is 2 to 3°C/day, but the cooling rate can be considerably larger if the upper layers have a higher temperature than normal. An increase in the ozone amount at the lower altitudes may cause the surface temperature of the earth to rise several degrees Celsius in order to restore infra‐red equilibrium, if no other factors change that produce an effect upon the heat balance. The pressure broadening and overlapping of the spectral lines have been taken into account in these calculations together with all other physical phenomena that are known to be of importance to the problem. An estimate is given for the accuracy of the results.
Local temperature variations in the Reading area
Authors: Parry M. 
Published: February 2007

AbstractThe following paper describes some results of an investigation of local climate — based on a close network of meteorological stations — undertaken over an 18‐month period in the Reading area. Mean and extreme temperatures, and temperature distributions on selected occasions are examined in relation to the local factors involved: these are mainly the relief and the presence of the town. In particular, the relation between weather conditions and variations in minimum temperatures is considered. Diurnal temperature variations at different sites are compared. Although the local relief is slight and the urban area neither closely built up nor heavily polluted, temperature differences of up to 8°F can occur, and differences in minima of 4°–5° are common, during radiation nights. Maximum temperatures vary little.
Variation of temperature in the troposphere and lower stratosphere
Authors: Bannon J. K. , Gilchrist A. 
Published: February 2007

AbstractCorrelation coefficients are evaluated between temperatures at 500 mb and at three levels in the lower stratosphere (highest 60 mb) and, respectively, the pressure at the tropopause and the height of the 300‐mb level for Larkhill and Lerwick for each month of the year. Similar coefficients are also given for Malta and (for different levels) for Arctic Bay for January, April, July and October. The Dines type of relationship is confirmed for those regions and seasons affected by travelling depressions and anticyclones. There is no significant correlation between similar parameters for Aden and tropical islands in the Pacific. The relation between temperature in the lower stratosphere and, respectively, the level of the tropopause and the height of the 300‐mb level decreases by a factor of 2 or more between the levels of 150 mb and 60 mb at Larkhill, Lerwick and Malta, indicating a marked decrease with height in the effect of tropospheric disturbances on stratospheric temperatures. The stratospheric correlation coefficients for Larkhill and Lerwick have a significant minimum in the winter.
The study of air pollution with the electron microscope
Authors: Cartwright J. , Nagelschmidt G. , Skidmore J. W. 
Published: February 2007

AbstractThe use of electron microscopy for observation and measurement of solid particles in air pollution is described, the thermal precipitator being used as sampling instrument. By using heat‐stable membranes, it is possible to distinguish combustible from non‐combustible matter, and other chemical tests can be used to distinguish different materials.The shape of the particles in air pollution is mainly spherical; the size varies from 0.01 to 1 μ, although occasional larger particles are found. Many of the spheres are aggregated and resemble carbon black.Examples are given of quantitative evaluation in terms of weight per unit volume for different size classes. The few results obtained so far show reasonable agreement with previous mass estimates based on smoke‐filter sampling. The future developments in the use of the electron microscope for studying air pollution are briefly discussed.
The use of a stream function in a two‐parameter model of the atmosphere
Authors: Bushby F. H. , Huckle Vera M. 
Published: February 2007

AbstractIn an attempt to obtain a better approximation to the horizontal flow of a non‐divergent fluid than the geostrophic approximation, a Monge‐Ampère type of partial differential equation, similar to that of Charney (1955), is derived to enable a stream function to be found from the contour height field. A method is given for the numerical solution of this equation.The stream function has been used in place of the contour height parameter to represent the flow at the mean level in computing three 24 hr forecasts based on the Sawyer‐Bushby two‐parameter model of the atmosphere, and the results are compared with similar computations without the stream function.In one situation, the use of the stream function produced a marked improvement in the computation.
Space and time variations of charged nuclei and electrical conductivity of the atmosphere
Authors: Sagalyn Rita C. , Faucher G. A. 
Published: February 2007

AbstractThe time variations of electrical conductivity and charged nucleus concentration have been investigated in fair weather in the altitude range 700 to 15,000 ft above the surface. In the exchange layer regular variations of nucleus concentration with time are observed from around sunrise to early afternoon. Analysis of the meteorological data obtained simultaneously shows that this variation is due primarily to the daily turbulent cycle. During periods of low advection, regular variations of nucleus concentration with time from early afternoon to the following sunrise are also observed in this region, and are shown to be the result of nucleus coagulation and subsidence. The time variations at night are more complicated during periods of intense advection. Above the exchange layer variations in nucleus content with time are not found to be regular. The variations in electrical conductivity with time are the inverse of the changes in nucleus concentration. The observed relation between conductivity and nucleus concentration is in good agreement with the theory of small ion balance, using Thomson's theory for small ion volume recombination and Bricard's theory for collisions between small ions and nuclei. An analysis of observed daily variations in the magnitude of the horizontal fluctuations of these variables is also given.
A contribution to absolute pyrheliometry
Authors: Drummond A. J. 
Published: February 2007

AbstractThe results are presented of comparisons made in Southern Africa, during the years 1951–1954, between pyrheliometers of the Ångström type which had been standardized at Davos (Switzerland), Leopoldville (Belgian Congo), Pretoria (South Africa) and Stockholm (Sweden). A section is also devoted to an investigation into the relationship between the original Ångström scale and the embodied in the Abbot pattern of actinometer of the Smithsonian Institution, Washington. This latter series of comparisons was made at Pretoria (altitude 1370 m), under normal conditions of cloudless sky with reasonably steayd atmospheric transmission.The programme was extended to include a comparison between specimens of these two sub‐standard radiometers using a controlled laboratory source of radiation. In these conditions, the radiometers were found to agree to within one‐half per cent. This is further evidence of the small divergence (first pointed out by Guild in 1937) of the scale originated long ago by Knut Ångström, from the true standard of radiometry.
The melting point of diphenyl ether as a self‐maintaining reference temperature in an equatorial climate
Authors: Webb C. G. 
Published: February 2007

AbstractIt is possible, and convenient, in an equatorial climate to use the melting point of diphenyl ether (26.6°C) as a thermocouple reference temperature which, under specified conditions, will be self‐maintaining in the open air to within ± 0.1°C for periods of about a fortnight, the ambient temperature range being ± 5°C.
The use of balloons in atmospheric pollution research
Authors: Lucas D. H. , Spurr G. , Williams F. 
Published: February 2007

AbstractAn experimental technique has been established for measuring the rise of a plume from a stack, the ground‐level concentrations produced and the rates of deposition of dust emitted in the plume. It can be applied over distances where plumes from power stations are not normally visible. It can be used to give a result before weather and station conditions have changed appreciably and therefore produces information which can conveniently be compared with theoretical estimates.
Patterns of hailstorms in Alberta
Authors: Douglas R. H. , Hitschfeld W. 
Published: February 2007

AbstractBetween 14 June and 20 September 1957, nearly 3,200 surface reports of hail were collected in a 15,000 sq. mile area. Information included location, time and duration of hail and the largest size of hail encountered. Continuous radar records of the storm pattern were taken in a manner suitable for the preparation of constant‐altitude radar weather (CAPI) maps, to a range of 100 miles.At times, hail fell soon after a first echo (possibly within 10 min), sometimes no hail occurred for as long as an hour or two. Usually, the hail fell in short bursts (lasting up to 20 min and spread over a few miles) which would appear to be the products of single storm cells. But on several occasions (notably on 23 July) hail fell continuously for 11/2 hours and, without evidence of a multiplicity of cells, covered a strip 30 mi long. Sustained hail came from storms whose echo tops were steady close to 30 kft above surface. Hail associated with echoes of lesser height was not continuous and tended to fall in bursts which sometimes followed closely on the merger of previously separate storms. A study of 83 independent echoes showed that the probability of hail from a given storm was clearly related to maximum height of the storm, rising from zero for storms 10 kft or lower, to 100 per cent for storms 38 kft or more in height. A similar correlation holds between echo height of a hailstorm at any instant and hail arrival at the ground some minutes later.
Some observations of potential evaporation, 1955–1957
Authors: Green F. H. W. 
Published: February 2007

AbstractThe methods of interpreting routine observations with an apparatus designed to measure potential evaporation (PE) are discussed, and tables of results are presented. With a view to standardizing PE measurements, conditions are defined, resembling those for standard climatological stations. Difficulties in the interpretation of daily observations, because of various kinds of time‐lag, and variations in storage of water in the apparatus, have been encountered but largely overcome. The values obtained are compared with those computed from other available data by the methods of Penman, Thornthwaite, and Crowe, in which the conditions are either specified, or tacitly assumed, to be similar. The values are in general agreement, but it is shown that at west coast stations in Britain the observed values tend to be lower than the computed, and, more strikingly, that at high‐altitude stations, they tend to be higher.
Research on methods of forecasting storm surges on the east and south coasts of Great Britain
Authors: Rossiter J. R. 
Published: February 2007

AbstractRecent work at the Tidal Institute has provided means of predicting storm surges at the River Tyne entrance, Immingham, King's Lynn, Lowestoft and Southend in the North Sea and Newhaven in the English Channel, from meteorological forecasts.An investigation of surges at Aberdeen has not resulted in a completely satisfactory method of predicting external surges, which are generated outside the North Sea, so that their effects at ports further south have been allowed for by observing their magnitude at Aberdeen and applying an empirical rule which governs their amplification and rate of travel, after Corkan (1948). The disturbances generated inside the North Sea proper, at all the other North Sea ports except King's Lynn, have been correlated at intervals of 6 hr with quantities representing the tractive force of the gradient winds at chosen points in the sea, assuming a quadratic law of friction. The success of the formulae so produced is fully illustrated. For King's Lynn, tide and surge have been treated as an entity, and high‐ and low‐water heights have been expressed as functions of the corresponding heights at the River Tyne and the local wind strength and direction.The propagation of North Sea surges through the Straits of Dover has been studied using Newhaven observations, and it is shown that they travel from Lowestoft as free progressive waves, being attenuated by half. Depressions in the western approaches to the English Channel are also shown to be responsible for disturbances at Newhaven.
A method of determining the constant in the balloon‐ascent formula
Authors: Sinha K. L. 
Published: February 2007

AbstractExpressing the coefficient q, of the rate‐of‐ascent formula of the balloon (e.g. V = q F1/2/(W + F)1/3, where V is the rate of ascent of the balloon, W the weight of the balloon and F the free‐lift) in terms of the coefficient of aerodynamic resistance κ of the balloon, a curve of q as a function of the Reynolds number N is worked out. Introducing a κN2 – N curve, the value of q, appropriate to a balloon flight is obtained.