bluuebunny/crossref_metadata_2025_split huggingface dataset:
The modification of continental polar air over Hudson Bay
Authors: Burbidge F. E. 
Published: February 2007

AbstractChanges in the physical properties of continental polar air are studied for air currents with trajectories over the Hudson Bay region. Computations indicate that westerly air streams crossing Hudson Bay in early winter are modified to a depth of 5 to 10 thousand ft. By midwinter, however, the modification is found to be negligible. This lack of modification in midwinter is attributed to the formation of an ice surface on Hudson Bay. Changes in the climate of the surrounding area caused by the formation of ice on Hudson Bay are illustrated by changes in temperature, cloud and snowfall. The modifying influence of the Bay in cooling the air in summer and heating the air in early winter is also discussed.
The evaluation of vertical velocity and thickness tendency from Sutcliffe's theory
Authors: Bushby F. H. 
Published: February 2007

AbstractThe field of mean vertical velocity in the 1,000–500 mb layer of the atmosphere due to large‐scale atmospheric systems is computed for six synoptic situations. The method is based on the Sutcliffe ‘development’ theory and an atmospheric model is used in which the isobaric divergence of the velocity field is taken to be a linear function of pressure passing through a level of non‐divergence in mid‐troposphere. The effect of vertical stability on vertical velocity is examined.The components of thickness tendency due to the computed vertical velocity are evaluated and compared with the differences between the observed thickness changes and their advective components. Some reference is made to the relationship between vertical velocity and rate of rainfall.General results apparent from the six situations examined are stated and one situation is described in detail. It is concluded that in middle latitudes the difference in vertical velocity between an ordinary stable and a neutral atmosphere may frequently be fourfold and that the component of thickness tendency evaluated from the computed vertical velocity gives a reasonable estimate of the effect of vertical motion on changes in thickness.
The initiation of cyclonic circulation in a vertically unstable stagnant air mass
Authors: Haque S. M. A. 
Published: February 2007

AbstractEquations of motion are derived in cylindrical co‐ordinates and they are applied to investigate the perturbations in a vertically unstable stagnant air mass having infinite lateral extent and confined between two horizontal planes. A complete solution of the perturbation equation with the boundary conditions is derived. The boundary conditions are then varied by surrounding and surmounting the unstable air mass by stable air. It is shown that the horizontal extent of the unstable air mass has a definite upper limit which depends on the magnitude of instability, height of the disturbance, and the Coriolis parameter.The mathematical analysis is then applied to show that a tropical cyclone may originate from vertical instability. It is shown by a numerical illustration that the distribution and order of magnitude of the different meteorological elements are the same in the mathematical model as observed in the initial stages of a tropical cyclone.
The mean temperature of central England, 1698–1952
Authors: Manley Gordon 
Published: February 2007

AbstractA table of monthly mean temperatures representative of the English Midlands has been constructed for the period 1698–1952. From 1815 it is derived from the average of the ‘Radcliffe’ (Oxford) and ‘Lancashire’ monthly means. From 1771–1815 it has been built up by averaging the departures, or anomalies, for each month at a number of inland stations whose records are long enough to be bridged into the years 1815–1840; from 1771–1798 the values thus obtained are reinforced by direct values based on the long Midland record at Lyndon. Before 1771 the existing Edinburgh, Greenwich and Lancashire means are supplemented by further direct values based on Lyndon and Exeter. For all years previous to 1752 the Old Style calendar months have been rectified to the New Style, and the direct values derived from early MS. journals in London, Plymouth, and the Midlands have been carefully collated back to 1728, and extended by means of other short records from Halifax, London and elsewhere back to November 1722. Finally, a direct reduction of Derham's Upminster record, 1699–1706, has been used as a basis for the earliest years. For the intervening years estimates are provided from a consideration of the Utrecht reductions, supplemented for 1713–1722 by non‐instrumental observations of wind and weather in England. Some corroboration of the values so obtained during the eighteenth century is provided; it is hoped that the table can serve as a general standard for studies of English temperature variations until such time as something better can be provided.
The dynamical influence of large‐scale heat sources and sinks on the quasi‐stationary mean motions of the atmosphere
Authors: Smagorinsky J. 
Published: February 2007

AbstractThe classical convective theory for the influence of large‐scale zonally asymmetric heating and cooling on the quasi‐stationary mean motions is re‐examined and shown to be inconsistent with observation. Scale considerations indicate that the classical mechanism cannot be applied to heating on a scale larger than that responsible for sea‐breezes. In analogy with the theory of orographically produced stationary disturbances, heat sources and sinks of planetary dimensions produce quasi‐static and quasi‐geostrophic perturbations. A thermally active model is constructed in which all motions except those of large scale are filtered out a priori. The small perturbations produced by an idealized large‐scale distribution of heat sources and sinks acting on a horizontally uniform baroclinic zonal current confined between rigid horizontal planes are then studied. The influence of surface friction is taken into account. Calculations are also performed on a model with no friction and on the assumption that entropy is advected horizontally. The results generally show good agreement with those for the more general model. When the stratosphere is taken into account, the disturbances in the upper troposphere are reduced in magnitude. The conditions for resonance in the absence of friction are determined. The passage through the resonant state is shown to modify significantly the character of the motions. The observed normals are discussed at some length in light of the theoretical computations. It is found that the magnitude and spatial distribution of the model disturbances display substantial correspondence with observation when allowance is made for orographic effects. Finally a method is suggested for quantitatively deducing the three‐dimensional field of non‐adiabatic heating and cooling from the observed normal maps by dynamical considerations.
Turbulence in the upper air, as shown by radar‐wind and radiosonde measurements
Authors: Scrase F. J. 
Published: February 2007

AbstractObservations of the fluctuations, minute by minute, of wind components and temperature in a radiosonde and radar‐wind ascent up to 30 km were analysed. After allowing for the effects of random errors a standard deviation of about 4 kt for the eddy velocity, with a mean wind of about 25 kt, was obtained. The standard deviation of the temperature fluctuations was 0.85.F in the troposphere but decreased to about one‐third of this in the upper stratosphere.
Properties of spectra of atmospheric turbulence at 100 metres
Authors: Panofsky Hans A. , McCormick Robert A. 
Published: February 2007

AbstractThe properties of spectra of vertical and horizontal turbulence and of their cross‐spectra, at elevations near 100m, are summarized; a few spectra from lower levels are considered. The following tentative conclusions are drawn:

At frequencies of the order of 100c/hr and above, the spectral intensity is proportional to the square of the mean wind speed and essentially independent of the radiation intensity. At lower frequencies, the ratio of spectral intensity to the square of the wind speed increases with increasing incoming radiation.
The intensity‐ratio of the co‐spectrum of vertical and horizontal velocity to the spectrum of vertical velocity increases with increasing wind shear. It also decreases with increasing frequency, n, approximately as n−1.
At low frequencies, the spectral intensity of the horizontal velocity components is generally much large than that of the vertical velocity. At high frequencies, the spectral intensities of all velocity components are of the same order of magnitude. At low frequencies, the ratio of vertical to horizontal spectral density increases with increasing radiation.
The quadrature spectra at a given frequency tend to be negative with large radiation, positive with little radiation. This indicates that edies are low and wide with little radiation, and tall with much radiation.
The frequency at the maximum of the vertical velocity spectrum decreases with increasing height and increasing radiation intensity.
The ratio of tubulent to mean energy is somewhat larger for air with over‐land trajectories than for air with oceanic trajectories.
Soil temperatures in an afforested area in Aberdeenshire
Authors: Coutts J. R. H. 
Published: February 2007

AbstractContinuous records have been maintained since January 1952 of soil temperatures in a forestry plantation near Ballater, Aberdeenshire. The data have led to the following conclusions:
The mean annual temperatures are practically the same throughout the soil profile.
Inversions of the temperature profile occur in April and August.
The frost‐free periods have been June to September in the air and May to October in the soil at a depth of 1 in. Frosting at a depth of 6 in. has been restricted to the months of December and January, and no frost temperatures have been recorded at depths of 12 in. or more.
During the two years 1952 and 1953 temperatures of 0°C or less have been noted on 167 days in the air, 109 days at a depth of 1 in., and 12 days at a depth of 6 in.
There is severe damping of temperature amplitudes with increasing depth, the diurnal variations being very small at depths exceeding 12 in. Estimates of thermal diffusivities have been made for the soil strata from ground level to 1 in. and from 1 in. to 6 in.
It is found that good estimates of weekly mean temperatures can be obtained from readings of the daily maximum and minimum temperatures.
Continuous convection from an isolated source of heat
Authors: Priestley C. H. B. , Ball F. K. 
Published: February 2007

AbstractLaws are derived for the variation of vertical velocity, w, and temperature, θ, with height, z, above a continuous circular source of heat of finite extent, on the assumptions that the lateral profiles are of similar shape at different distances above the source and that the resistance is a quadratic function of w. The lateral profiles are then taken to be Gaussian, though not all the properties deduced are dependent on this assumption. Complete solutions are obtained allowing for the thermal stratification of the environment; unless this stratification is neutral the common assumption that the vertical heat flux is constant with height is no longer true.It is shown that the width of the column will increase uniformly with height. In general w increases with z at low elevations and then decreases, but this second stage does not occur when the environmental lapse rate is large and the source area sufficiently extensive. Under superadiabatic conditions the second stage, when it occurs, is followed by a third stage in which w increases again without limit; under subadiabatic conditions w decreases rather abruptly to zero at a certain ‘ceiling’ height, for which a simple approximate formula is derived.Numerical values illustrate the application of the solutions to problems of atmospheric pollution, frost prevention, and dry thermals. The solution for neutral conditions is compared with Railston's laboratory measurements.
The general circulation of the atmosphere: A numerical experiment
Authors: Phillips Norman A. 
Published: February 2007

AbstractA long‐period numerical forecast is made with a two‐level quasi‐geostrophic model, starting with an atmosphere in relative rest. Both friction and non‐adiabatic effects are included in the equations, the latter as a linear function of latitude. Principal empirical elements in the experiment are the intensity of the heating, the value of the vertical stability, and the type of frictional dissipation. The flow patterns which develop are quite realistic, including a jet and zonal surface westerlies in middle latitudes, and the growth of a large disturbance. The associated energy transformations are investigated, and demonstrate the important role of the disturbance in the development of the zonal currents. The meridional circulation is also studied, together with its contribution to the zonal momentum budgets of the lower and upper halves of the atmosphere. Truncation errors eventually put an end to the forecast by producing a large fictitious increase in energy.
Dew
Authors: Monteith J. L. 
Published: February 2007

AbstractDew formation on short grass has been studied with a balance, recording weight of condensation, and with filter papers to absorb moisture. Three regimes are distinguished: in the first, daytime evaporation continues and the grass remains dry; in the second, the surface continues to lose weight but the grass becomes wet owing to the partial condensation of water vapour evaporating from the soil; in the third, this loss of weight ceases or there is an increase in weight attributed to condensation of atmospheric water vapour. A distinction is therefore made between ‘distillation’ of water vapour from soil to grass (1–2 mg cm−2hr−1) occurring on very calm nights through a laminar layer with a transfer coefficient approaching the molecular value; and ‘dewfall,’ the turbulent transfer of water vapour from the atmosphere, negligible when the wind at 2 m falls below 0.5 m/sec but reaching 3–4 mg cm−2hr−1 with stronger winds. This distinction is supported by analysis of the surface heat‐budget. On windless nights, since heat flux from the soil and net radiative loss were almost equal, the transfers of sensible and latent heat from the atmosphere were negligible and distillation was of much greater importance than dewfall. Implications for taller crops and warmer climates are briefly considered.
The empirical relation between solar radiation and hours of sunshine
Authors: Glover J. , McCulloch J. S. G. 
Published: February 2007

AbstractThe variation with latitude of the regression parameters a and b in the conventional equation of Ångström type

between total solar radiation on a horizontal surface (Q) and hours of bright sunshine (n) has been examined. It has been shown that the slope of the relationship b is effectively constant, while the threshold value a is a function of latitude. An empirical relationship leading to the Ångström equation at each latitude ϕ over the range 0° ‐ 60° is derived and is shown to give values in reasonable accord with previous experience. It is
On the grid length to be adopted in numerical weather prediction
Authors: Knighting E. 
Published: February 2007

AbstractThe predictive equations of numerical forecasting are cast in differential form and do not have simple analytic solutions. In practice, the finite‐difference analogues of the differential equations are solved using a grid and the grid length has been chosen so that significant features of the synoptic chart are reasonably defined by values at the grid points of contour height or pressure. The purpose of this note is to enquire into the grid lengths that should be chosen so as to make the best estimate of the derivatives which appear in the equations.
Notes on the wind flow at 50 mb in tropical and sub‐tropical regions in January 1957 and January 1958
Authors: Ebdon R. A. 
Published: February 2007

AbstractIn January 1957 the mean 50 mb flow pattern was persistently E'ly over large areas near the Equator and this is compared with the flow pattern of January 1958 which was predominantly W'ly over much the same area. The mean vector winds for Canton Island for six Januarys show a remarkable 2‐yr periodicity and suggest that either an E'ly or W'ly flow is equally likely to occur.
Ice‐nucleating properties of clay minerals and stony meteorites
Authors: Mason B. J. 
Published: February 2007

AbstractThe ice‐nucleating properties of clay minerals have been investigated in relation to their crystalline and surface structures. The kaolin minerals, the illites and halloysite are the most effective and important, their threshold temperatures for ice nucleation lying between −9°Cand −12°C. Minerals of the montmorillonite group and related forms are active only below −15°C. The relative contributions which the various clay minerals are likely to make to the ice‐nucleus content of the atmosphere are discussed in relation to their natural abundance, wind‐borne dispersion and particle size. Kaolinite is considered to be the most important source of highly efficient nuclei in confirmation of results obtained earlier by Mason and Maybank (1958).Tests on three new specimens of stony meteorites showed them to be inactive at −17°C.
Climatic change through geological time in the light of the palaeomagnetic evidence for polar wandering and continental drift
Authors: Runcorn S. K. 
Published: February 2007

AbstractThe key to the understanding of the gross changes of climate throughout geological time indicated by the geological record in the various continents depends on finding a physical method of determining latitudes in the geological past. The palaeomagnetic method seems to be the most hopeful, but for this one must assume that the average geomagnetic field is a dipole along the axis of rotation. The palaeomagnetic evidence shows this to be true for late Tertiary times – the poles derived from the mean palaeomagnetic directions of Tertiary rocks cluster about the present geographical pole and are distinctly different from the present position of the magnetic pole. There are strong theoretical grounds for believing that it has been true throughout the earth's history. The theory of the irregular fluctuations in the length of the day indicates that the rotation of the core and mantle are only weakly coupled. The electro‐magnetic torque to which this coupling is ascribed is variable because of the short term changes in the geomagnetic field. These fluctuations appear to accumulate with time and so there is always a small differential angular velocity between core and mantle, probably of either sign. Therefore, to an observer fixed on the earth's crust, the earth's magnetic field is axisymmetrical when averaged over periods of the order of the secular variation, i.e., extremely small times geologically speaking.The palaeomagnetic surveys of the various continents show systematic differences which, it appears, cannot be explained even by assuming that the earth's magnetic field was non‐dipolar, though axial, in times earlier than the Tertiary. Continental drift, as well as polar wandering, must therefore be inferred.There is a prima facie case that the latitudes thus inferred for the various continents from palaeomagnetic observations do agree with the commonly held inferences concerning the past climates of the earth made by geologists from the study of evaporite deposits, red beds, zonation of fossils, and glacial deposits. A new important check has been provided by palaeowind observations. The inference from the palaeomagnetic studies of Europe and North America that these continents were in low latitude between the Devonian and Triassic is consistent with the wind directions inferred from dune sandstones in Britain and the western United States. The consistency of the directions in the western United States over large distances seems to show that the winds were not affected by local geography.It appears that an explanation of Continental drift involves the hypothesis of convection currents in the earth's mantle which requires that the mantle is fluid when subjected to small stresses existing for many millions of years.
Short‐wave reflection coefficient for a field of maize
Authors: Graham W. G. , King K. M. 
Published: February 2007

AbstractHourly and daily determinations of the reflection coefficient for a field of maize (Zea mays) were made on 17 days from July to September 1958. An Eppley pyrheliometer was used to measure incident solar radiation and a Kipp solarimeter was used to measure reflected radiation. The hourly determinations showed increased reflection at low solar altitudes. With a moist soil, the reflection coefficient based on the daily radiation was 0·12 to 0·15 when the plants were small and 0·17 to 0·19 when the crop was fully developed. When the soil surface was dry and the plants small, the coefficient was 0·21. Tassel formation and freezing of the plants had no effect on reflection.
Large‐sphere limit of the radar back‐scattering coefficient
Authors: McDonald J. E. 
Published: February 2007

AbstractIn the limit of large scatterer diameters, the Mie theory must converge to geometrical optics. Previous results of Mie‐theory calculations of the radar back‐scattering coefficient σb have suggested that its large‐sphere limit is the ordinary reflection coefficient R of the scattering material. A proof that this is the asymptotic value of σb is given.
The use of smoothing or filtering operators in numerical forecasting
Authors: Wallington C. E. 
Published: February 2007

AbstractWith the view to improving numerical forecasts by damping the growth of spurious waves, particularly those with short wavelengths, smoothing operators have been applied to thickness and contour fields at intervals during the forecasting computations. There appears to be no simple objective method of determining sets of smoothing coefficients for the optimum improvement of a particular model, but preliminary attempts to smooth and improve numerical forecasts at Dunstable have been made on a trial and error basis. The results show the smoothing or filtering technique to be a powerful method of empirically improving numerical forecasts.
The electrification of frost deposits
Authors: Latham J. 
Published: February 2007

AbstractExperiments showed that the exposure of a frost deposit to an air‐stream caused ice splinters to be blown away from the deposit. These splinters were negatively charged if the air‐stream were warmer than the deposit, and positively charged if it were colder; if they were at the same temperature then no electrification was produced. In a typical experiment, with the frost deposit 10$C warmer than the air‐stream, the average charge carried away on a frost splinter was 6 × 10−7 e.s.u. These results can be explained, in sign and magnitude, by the Latham‐Mason theory of charge transfer associated with temperature gradients in ice; in the frost‐electrification experiments a temperature gradient was produced down a frost needle owing to the difference in temperature between the air‐stream and the frost deposit, thus causing the outer and inner tips of the needle to acquire equal and opposite charges. If the needle were then broken and blown off by the air‐stream it would carry away a charge of one sign leaving that of the other sign on the frost deposit on which it had grown; the sign of the observed charging was in agreement with the theory. Putting into the temperature‐gradient equations measured values of the dimensions of an ice splinter and the temperature difference between its ends it was possible to calculate the theoretical charge residing on the ends of an ice splinter; this value was found to be in good agreement with the measured average charge per splinter.