bluuebunny/crossref_metadata_2025_split huggingface dataset:
The microclimate of the potato crop
Authors: Broadbent L. 
Published: February 2007

AbstractShade temperatures and humidities in a standard screen and at an arbitrary level of 15 cm in potato crops were continuously recorded during three summers, 1947–49.In dry sunny periods : (1) the maximum temperature in the crop was from 0° to 13°F higher than in the screen, and over a period of eleven weeks in 1947 averaged 6°F higher (2) the crop minimum was about 2°F lower than in the screen (3) over a period of five weeks in 1949 the average daily mean temperature in the crop was 2.2°F higher than in the screen, and (4) the average daily temperature range was 8°F greater than in the screen.Wind, wet soil and cloudy weather greatly reduced these contrasts; occasionally the crop minimum was higher than the screen minimum.By day, humidity was higher in the crop than in the screen, the average difference at the minima being 5 per cent in relative humidity, and 7°F in dew point. By night, the dew point in the crop was, on average, 2°F lower than in the screen, corresponding to the observed difference in mean minimum air temperatures.During 1948 and 1949, more precise discontinuous records were taken of temperature, humidity and wind speed in and above potato crops with different densities of foliage in a variety of weather conditions. Temperature and humidity were measured at 10, 20 or 30, and 60 cm; wind at 20, 30 and 200 cm above ground level. In the crop there was only a slight temperature gradient in the early morning and throughout cloudy days, but during sunny days gradients were produced, depending on crop density; it was hottest at 10 cm in an open crop, at 30 cm in a dense crop; in both it was usually coolest at 60 cm when the soil was dry, but over wet soil the lowest temperature was found at 10 cm. Except on cloudy days, temperature inversion took place before sunset whatever the foliage density or moistness of the soil.Humidity (dew point) was usually greatest at 10 cm, but in a dense crop over dry soil water vapour transpired from the leaves often caused the air at 30 cm to be more humid than that at 10 cm.Wind affected both temperature and humidity by increasing lapse rates and causing rapid fluctuations within the crop, particularly of humidity. Changes of wind speed within the crop took place every few seconds, the amplitude of the fluctuations depending on the speed of the wind above the crop.
The measurement and recording of the heat flux into the soil
Authors: Deacon E. L. 
Published: February 2007

AbstractRelatively simple instruments for measuring the heat flux into or out of the soil are described together with methods of calibration. One form consists of a suitable metal disc of sandwich construction producing a thermal e.m.f. proportional to the heat flux through the disc, which is placed in the soil just below the surface.Details are also given of another form of flux plate which is suitable for continuous recording using a thread recording galvanometer.
Advective temperature change in the 1,000‐700 mb and 700‐500 mb layers
Authors: Craddock J. M. 
Published: February 2007

AbstractIt is shown, on the basis of about 700 measurements made at a particular station during six months, that the thermal change in the troposphere due to advection alone is largely offset by the other processes at work, so that the resultant change is a residual having a correlation of about 0.6 with the advective component.The shear hodograph of an upper wind sounding is shown to afford little useful information on the resultant thickness tendency.
Effect of turbulence and condensation on drop‐size distribution in cloud
Authors: Best A. C. 
Published: February 2007

AbstractEquations are developed to represent the rate of change of the number of drops of a given size in a cloud owing to condensation and to coalescence respectively. Numerical computation from these equations shows that condensation has a much greater effect than coalescence on drop‐size distribution in clouds with small average drop size, with small liquid‐water content or with a large degree of super‐saturation.With the assumption that drop‐size distribution in a cloud is governed by rate of condensation on the drops in the cloud and rate of turbulent diffusion of the drops out of the cloud it is then shown that the fractional volume of water comprised by drops smaller than a specified size is expressible in terms of an Incomplete Gamma function. In this Incomplete Gamma function the argument is 1·5 and the upper limit to the integral varies as the square of the drop size and is also proportional to a quantity which depends upon the degree of turbulence and upon parameters connected with the rate of condensation. It is shown that this theoretical formula approximates closely to a simpler formula already established empirically and that reasonable values for the coefficient of turbulence and the condensation parameters lead to a mean drop size which agrees closely with measured values.
A new method of stimulating convective clouds to produce rain and hail
Authors: Bowen E. G. 
Published: February 2007

AbstractThe theory of the formation of rain by coalescence leads logically to the suggestion that, if water drops of suitable size are sprayed into the base of a convective cloud, the drops will ascend in the upward air current, will grow by coalescence with the cloud droplets and may ultimately fall out as rain. Calculations show that under appropriate conditions the drops could attain a diameter greater than 1 mm and emerge from the base of the cloud from 20 to 60 min after water had been sprayed into it.Eleven experiments have been carried out to test the possibility of the method. In 10 cases, distinct changes occurred following the introduction of a water spray into the selected cloud. In 4 of these, virga fell from the cloud and it dissipated soon afterward. In 4 cases, rain or hail appeared shortly after spraying. On only one occasion were no results observed.The results suggest that the method might be useful for the artificial stimulation of rainfall, but further experiments are required to fully establish the mechanism.
The effect of a hedge on the flow of air
Authors: Rider N. E. 
Published: February 2007

AbstractExperiments are described in which the horizontal wind speed at three heights up to 2 m is measured at various distances up and down wind from a dense hedge 1·68 m high on occasions with wind directions approximately normal to the hedge. The results show that the hedge begins to exert an influence on the wind speed at 2 m at a distance equivalent to approximately 15 hedge heights upwind, and that downwind its influence extends to a distance approximately equivalent to 60 hedge heights. At the two lower heights of wind‐speed measurement the range over which the hedge has an effect is smaller. Diagrams are constructed to show the decrease in wind speed at the various heights within the distance range mentioned above.
Theory of air flow over a heated land mass
Authors: Smith R. C. 
Published: February 2007

AbstractThe velocity field of a stable atmosphere over and around a heated land mass is found, as a function of both time and distance, by consideration of the equations of motion, continuity and added heat. A heat function is introduced, in the last of these, which is not only fairly simple mathematically but also bears a good resemblance to the atmospheric picture. Certain terms are neglected initially to simplify the mathematics of the problem but they are used later to check the validity of the results and it is found that, in general, the solution would have been negligibly affected by the inclusion of these terms. There is difficulty in using the boundary condition at infinite height but this is overcome by evaluating the problem by two methods.The numerical work was done on the EDSAC at Cambridge and some graphs of these results, using a normal type of ground temperature distribution and lapse rate, are shown.
Investigation into the accuracy of four types of rainfall recorder
Authors: Lewis W. A. , Watkins L. H. 
Published: February 2007

AbstractThis paper describes four rainfall recorders and gives the results of laboratory and field investigations carried out at the Road Research Laboratory to determine the accuracy of the instruments.The instruments used were:
Standard Meteorological Office total‐rainfall recorder,
Meteorological Office rate‐of‐rainfall recorder,
Road Research Laboratory combined total‐rainfall and rate‐of‐rainfall recorder (orifice type).
Road Research Laboratory rate‐of‐rainfall recorder (channel type).
A laboratory study of the accuracy of the instruments was followed by examination of the records obtained of 49 storms occurring between the summer of 1951 and the autumn of 1952.It was found that mean rates of rainfall between given times could be measured within about 5 per cent from the records from all the instruments, but that the chart speed of the Meteorological Office total‐rainfall recorder is too slow for peak periods of short duration to be located accurately. The principal advantage of the Road Research Laboratory combined total‐rainfall and rate‐of‐rainfall recorder is that it provides a clear picture of the shape of the storm curve which is very helpful in the analysis of the records.
The evaluation of some regression coefficients for estimating the 150‐mb wind at Liverpool
Authors: Ellison T. H. , Walshaw C. D. 
Published: February 2007

AbstractThe regression coefficients of the 150‐mb wind at Liverpool in winter on (a) the 300‐mb wind and the 500‐mb wind jointly, (b) the 300‐mb wind alone, (c) the 150‐mb wind 12 and 24 hr previously, (d) the 150‐mb wind 12 hr previously alone and (e) 24 hr previously alone, have been computed from data for January and February 1950 to 1954 with the aid of an electronic digital computer. The single regression equations are found to be practically as useful as the double ones. 12‐hour forecasts using the regression equation compare favourably with those made by orthodox methods.
Energy changes involved in disturbing a dry atmosphere
Authors: Ball F. K. 
Published: February 2007

AbstractA method is presented for calculating the energy changes involved in disturbing a layer of a dry atmosphere. The special case of complete mixing is considered in detail and it is shown that this can only occur spontaneously when the Richardson number is less than one‐half. The kinetic energy absorbed or released when a layer of any thickness and lapse rate is completely mixed can be estimated from a graph. A second graph gives the kinetic energy necessary to maintain a given temperature gradient when heat is added to or withdrawn from any given level within the layer. Application to frost prevention shows that the energy required to maintain mixing in a 100‐ft layer while heat is being lost at the base is only a small fraction of the input energy from the normal design of frost fan.
Graphs of cumulative residuals
Authors: Kraus E. B. 
Published: February 2007

AbstractThe particular uses of cumulative residuals are demonstrated by two plots of annual Nile discharge at Aswan. It is shown that the mean regime of the Nile changed abruptly in 1898 in conformance with secular rainfall changes throughout most of the tropics. No trend is apparent in the two periods before and after 1898.
Waves in the lee of an isolated hill
Authors: Scorer R. S. , Wilkinson Mary 
Published: February 2007

AbstractA two‐dimensional ridge produces a system of lee waves parallel to it, in a suitable airstream. Synthesizing an isolated hill by superposition of ridges inclined at various angles but intersecting in a point, and representing this by an integral, the interference pattern of the lee‐wave systems of the component ridges has been computed. An isolated hill produces a lee‐wave pattern very similar to that produced by a ship moving across the surface of deep water. It is confined within a wedge‐shaped region, the corner of the wedge being vertical and through the hill top. The half‐angle of the wedge depends upon the airstream characteristics but is typically about 15°. The waves decrease in amplitude downstream like x−½. If an oval hill lies across the airstream an appreciale lee‐wave system will be produced but it is greatly reduced in amplitude if the major axis of the hill is turned through 30° or more from the normal to the airstream. The discussion is restricted, on account of its complexity, to airstreams composed of only two layers, in each of which the parameter l is independent of height.
An investigation into the generation of waves when the fetch of the wind is less than 100 miles
Authors: Darbyshire J. 
Published: February 2007

AbstractWave records taken at Lough Neagh by wave‐pressure recorders and waves recorded over the Irish Sea by an airborne wave recorder are used to investigate the variation of wave height and wave period with fetch and wind speed, when the fetch is below a hundred miles. For values of fetch below 1 mi, these observations are supplemented by measurements taken at Staines Reservoir.Empirical formulae are obtained for the maximum wave height, significant wave period, and spectral distribution of wave energy which reduce in the case of a large fetch to those already derived for waves in the open sea from weather ship observations. The formulae indicate that the steepness of the highest waves increases linearly with the wind speed and decreases with increasing fetch.An expression is obtained for the mean square slope as defined by Cox and Munk (1954) and, under certain conditions, agreement is found with their results.
The formation of large droplets in small cumulus
Authors: Mason B. J. , Ghosh D. K. 
Published: February 2007

AbstractDroplets of radius exceeding 30 μ are sometimes found in concentrations of order 100/l in non‐precipitating cumulus less than 5,000 ft in depth and having, on average, liquid‐water contents of only a few tenths of a gramme per m3. It is shown that droplets of this size may be produced by condensation and coalescence on hygroscopic nuclei of mass greater than 10−11 g entering the bases of such shallow clouds, provided that these last for at least one hour. The published concentrations of giant salt nuclei seem only just sufficient to account for the observed numbers of large droplets, but simultaneous measurements of both are urgently required.
Soil temperatures near Nairobi 1954‐1955
Authors: McCulloch J. S. G. 
Published: February 2007

AbstractContinuous records of soil temperature at Muguga, Kenya, (1° 13'S, 36° 38′E) under bare soil at nominal depths of one, three and six inches and one, two and three feet were taken for the period 1954–1955.The form of the temperature wave proved remarkably constant from day to day and the diurnal variation was measurable down to about one foot. The mean of maximum and minimum temperature is a good approximation to the daily mean temperature, as obtained by numerical integration, at depths of 6 in. and over. Nearer the surface, however, the mean of maximum and minimum gives an overestimate of the daily mean temperature. The annual soil temperature wave was not sufficiently marked to justify a mathematical analysis, but the mean diurnal wave for selected ten‐day periods was analysed and values of thermal diffusivity were computed for the depth ranges 1‐6 in. and 6‐14 in. Despite seasonal changes in soil moisture content, diffusivity values proved remarkably constant with mean values of 0·0020 and 0·0015 cm2 sec−1 respectively for the two depth ranges. There was no obvious correlation with soil water changes.
On the microstructure of atmospheric turbulence – A review of recent work in the U.S.S.R.
Authors: Obukhov A. M. , Yaglom A. M. 
Published: February 2007

AbstractOwing to turbulence the instantaneous distribution of wind velocity, temperature, humidity and other meteorological elements is of a very complicated character, the elements at different points undergoing random and often very considerable fluctuations. Similarly, the values of the same elements at a fixed point and at different moments are characterized by random fluctuations having a very wide spectrum. Space and time fluctuations of meteorological elements are of general geophysical interest since they characterize atmospheric turbulence which is one of the most important features of atmospheric motion. Moreover, the study of fluctuations has an applied significance as one needs to know the statistical characteristics of fluctuations for the determination of the rate of the turbulent exchange in the surface layer, for the theory of meteorological instruments and for a number of problems of atmospheric optics, atmospheric acoustics and radio‐meteorology.Because of their wide spectrum (both in space and time) the methods of study of these fluctuations vary according to the particular part of the spectrum which we are interested in. Here we shall mainly deal with the problem of small‐scale turbulence (of the micro‐inhomogeneities of the atmospheric fields) which are characterized by periods of a few hundredths of a second to some seconds and space scales of a few centimetres to some metres. Our considerations will mostly refer to the surface layer which has been most studied. In the U.S.S.R. a number of theoretical and experimental investigations concerning the microstructure of the principle meteorological fields, mainly those of the wind velocity and temperature, have recently been carried out. The results of these investigations are in satisfactory agreement. Simultaneously some special problems of the physics of the atmosphere using the above‐mentioned results have been treated. A brief review of all the investigations is given below.
Exchange of heat, moisture and momentum between Hurricane Ella (1958) and its environment
Authors: Gangopadhyaya M. , Riehl H. 
Published: February 2007

AbstractOn 2 September 1958, a tropical storm moved near the centre of the network of upper‐air observations in the Atlantic and Caribbean SE of Florida. This made possible determination of the structure of the storm at a radius of 4·5° latitude from the centre through the entire troposphere and computation of surface integrals concerning the exchange of heat moisture and momentum between the storm and its surroundings. It was found that a net heat export occurred, indicating a net tropospheric drying and cooling after inclusion of the effect of radiation. The inward transport of relative angular momentum was insufficient to balance the flux of angular momentum to the ground as estimated from calculations for the mean hurricane. These computations then suggest weakening of the disturbance with time, and this actually occurred.
Utility of stretch vector correlation coefficients
Authors: Charles B. N. 
Published: February 2007

AbstractThis paper compares empirical values of the vector stretch correlation coefficient, and the total vector correlation as fundamentally defined. The former is apparently sufficiently accurate when applied to temporal stretch alone, up to three days, but when applied to space stretch it may have little meteorological meaning unless it exceeds about 0·3 in large data samples (about 450 daily observations).
Photolytic de‐activation of silver iodide as an ice‐forming nucleus
Authors: Bryant G. W. , Mason B. J. 
Published: February 2007

AbstractThe rate at which the ice‐nucleating ability of silver iodide decays when irradiated with the equivalent of strong sunlight has been determined by measuring the density of oriented ice crystals appearing on single crystals of silver iodide after various periods of exposure to a mercury‐arc lamp. Wavelengths greater than 4,400 Å cause very little photolysis and decay of nucleation. The ice‐crystal density decreases 10‐ to 20‐fold after the silver iodide has been exposed to the equivalent of one hour's strong sunlight; this result is in fair agreement with the findings of the Australian workers where the activity of silver‐iodide smoke falls by 1 to 2 orders of magnitude after one hour in the atmosphere in sunlight.
Some recent changes in atmospheric electricity and their cause
Authors: Stewart K. H. 
Published: February 2007

AbstractAnnual mean values of atmospheric electrical potential gradient are tabulated for three British and two Portuguese stations and it is shown that unusual changes have occurred since 1952. These changes could be explained by an increased conductivity of the air near the ground. Measurements of β‐ray ionization made at the British stations indicate that the increase in conductivity has been produced by a surface deposit of radioactive material attributable to nuclear‐test explosions.
The fallspeeds of hailstones
Authors: Macklin W. C. , Ludlam F. H. 
Published: February 2007

AbstractMeasurements have been made of the speeds of ice objects resembling hailstones during free fall, and of the drag coefficients of such objects and of natural hailstones. It has been found that the drag coefficients range from those of spheres (about 0·45) to about 0·8, depending on the shape and surface characteristics of the stone.
Precipitation over the North Atlantic Ocean
Authors: Tucker G. B. 
Published: February 2007

AbstractThe frequency of various types of ‘present‐weather’ observations are analysed and a method is derived using these to obtain estimates of mean monthly precipitation. The method is applied to observations from ocean weather ships in the North Atlantic Ocean to obtain the mean monthly, seasonal and annual precipitation over the ocean during the five‐year period 1953 to 1957. The results are then compared with previous estimates.
The spectrum of horizontal gustiness near the ground in high winds
Authors: Davenport A. G. 
Published: February 2007

AbstractResults of a study of about 70 spectra of the horizontal components of gustiness in strong winds are described. From these and other published data the following expression for the spectrum of gustiness for strong winds in the lower layers is suggested:magnified imageCross‐spectra and cross‐correlations of velocity between pairs of stations on a mast are given. From this it appears that the cross‐spectra can be expressed as a simple function of the ratio of the vertical separation to the wavelength, no dependence on height being detectable.
The energy balance of an evaporation pan and the measurement of the reflectivity of its bottom
Authors: Wartena L. , Borghorst A. J. W. 
Published: February 2007

AbstractA U.S. Weather Bureau Class A evaporation pan was used for micro‐meteorological measurements in Iraq. Because it seemed doubtful if the method of the U.S. Weather Bureau could be used for working up the data in the desert climate of Iraq, the energy balance of the pan was studied, and details are published elsewhere. The considered items are summed up in this contribution and the results are given in Table 1. The problem of the albedo for sunlight of the shallow water in the pan was studied in the laboratory. Measurements were taken with a filtered lightbeam and a silicon photo‐cell. In a zinc pan filled with 0·175 m water, 8 per cent of the direct and diffuse sunlight with wavelengths < 1 μ which has penetrated through the water surface is reflected.
Scale analysis of atmospheric turbulence at 2 m
Authors: Panofsky H. A. 
Published: February 2007

AbstractVarious horizontal scales of the horizontal wind components are compared in stable and unstable air. In stable air the scales are small, and those along the wind are larger than the scales across the wind. In unstable air the scales are large and about the same in all directions.The speed of translation of turbulent patterns normally does not deviate much from the wind speed, with one curious exception.The ratio of the Lagrangian scale of lateral component to the Eulerian scale of lateral component averages about 5 in stable air with moderate winds, but is tentatively suggested to be considerably smaller in unstable air.