bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of the Piche evaporimeter in the calculation of evaporation
Authors: Stanhill G. 
Published: February 2007

AbstractWater loss measured by the Piche evaporimeter, E, was found to be highly correlated with the calculated aerodynamic term, Ea, in Penman's evaporation formula. The error introduced by using the more convenient Piche evaporimeter measurements was less than that caused by the use of a single daily observation of vapour pressure in the calculation of the aerodynamic term.No significant difference was found between the relationship in the Judean hills and the arid Negev region of Israel which wasA test of a simplified form of Penman's formula, based on local Piche evaporimeter readings for the aerodynamic term and a regional value for the energy term, gave close agreement with the evaporation values calculated using the full formula.
The upper atmosphere in motion
Authors: Hines C. O. 
Published: February 2007

AbstractThe atmosphere above 80 km exhibits a wide range of dynamical phenomena. These are largely hydrodynamic in nature, and their sources of energy are likely to lie principally at lower levels. The regions are ionized, however, and hydromagnetically controlled motions also exist. They are generated from above as well as below.The observational evidence is reviewed broadly here, in groupings determined by the physical processes that are thought to be operative, and the corresponding theories are measured against it. Many shortcomings are disclosed and assessed, and profitable avenues for future research are tentatively explored. Several areas are indicated in which the dynamical processes modify other features of the upper atmosphere, but these are not analysed in detail.
The density and structure of hailstones
Authors: Browning K. A. , Ludlam F. H. , Macklin W. C. 
Published: February 2007

AbstractMacklin's (1962) experimental study of ice accretions, together with estimates of the typical conditions in the cumulonimbus of cold air masses and of summer continental air masses, is used to deduce the density of ice in the hailstones produced by these clouds. It is shown that generally small hail has a low density; it may reach the ground in the cold air masses but melts into rain in summer conditions. Large hail may have a low density core if grown upon a small frozen cloud droplet, but otherwise always has a high density. The presence of alternate layers of cloudy and clear ice is attributed to transitions between dry and wet growth.It is shown that large hailstones can be grown during a slow second ascent in a steady updraught whose speed increases with height. Under certain simplifying assumptions it is also established that their surface temperatures are then always close to 0$C, and therefore that minor fluctuations in cloud liquid‐water content may cause growth transitions. When the simplifications are removed this result cannot be demonstrated, but it seems reasonable that alternate layers of clear and opaque ice could be produced in a similar way, and need not indicate successive rises and falls in an intermittent updraught, as formerly thought.
Production of ice crystals and electric charge by splintering of freezing droplets in thunderclouds
Authors: Browning K. A. , Mason B. J. 
Published: February 2007

AbstractAccording to the Mason‐Latham mechanism the main thunderstorm charge is generated by the impaction, freezing and splintering of supercooled droplets on pellets of soft hail. The rates of charge and splinter production are now calculated using the Ludlam‐Browning model of the thunderstorm. The riming mechanism appears capable of producing charge at the required rate of about 1 amp in the region of strong updraught if large cloud droplets of r > 25 μ are present in concentrations of ∼ 10 cm−3 near the 0$C level. Splintering of these droplets while freezing on pellets of soft hail would produce ice crystals in concentrations about one‐tenth those of the large droplets between the — 20$C and — 30$C levels. The calculations indicate that the bulk of the thunderstorm charge cannot be generated and separated in regions of weak updraught because the production of splinters would lead to rapid glaciation of the cloud and the disappearance of supercooled water droplets.
Persistent temperature regimes at Kew
Authors: Craddock J. M. 
Published: February 2007

AbstractThe 5‐day mean temperature anomalies observed at Kew during the years 1901 to 1961 are examined for evidence of any pattern of variation characteristic of the time of year. It appears that the tendency for the existing temperature regime to persist is weak in spring and autumn, and stronger in winter and summer, being strongest of all in the late summer.
A long‐term series of monthly rainfall for Malta ‐ 1841 to 1961
Authors: Mitchell P. K. , Gregory S. 
Published: February 2007

AbstractPreviously published long‐term series are critically examined in the light of manuscript, primary printed and parallel records. All recently compiled series are shown to be inadequate. A new, but not entirely complete, series is proposed as a standard for Malta covering the 120 years from January 1841 to July 1961.
Sea smoke and steam fog
Authors: Saunders P. M. 
Published: February 2007

AbstractThe characteristics of fogs resulting from the advection of cold air over warm water (steam fog and sea smoke) are investigated. They are found to occur with air temperatures between 5 and 40°C lower than the water temperature, in winds from calm to gale; they have liquid water contents in the range 0·01‐0·5 gm−3, extend in height from 1 to 1,500 m and commonly exhibit either a columnar or banded structure. A study of their occurrence in Atlantic waters reveals a marked concentration in the western regions in the winter months because of the proximity of warm ocean and cold continent.Through the use of equations for turbulent transfer it is shown that the occurrence of steaming is related to the well‐known fact that two masses of unsaturated air at different temperatures when mixed together can yield a supersaturated or foggy mixture. In deriving the connexion the equality of transfer coefficients for heat and water vapour is assumed.The circumstances in which steaming occurs are defined. the difference in the temperatures of the air and water must exceed a threshold which is dependent on the humidity of the air and the temperature and salinity of the water: its value, in the range 5·15°C, is a minimum when the air is moist and the water cold and fresh. the liquid water content and vertical extent of steaming increase as the thermal contrast increases. Close agreement is found between observations of the onset of steaming and the computed threshold values.
Lagrangian and eulerian correlations and energy spectra of geostrophic velocities
Authors: Kao S.‐K. , Bullock W. S. 
Published: February 2007

AbstractAn analysis is made of the dispersion of the end‐points of geostrophic trajectories initiated daily at 0000Z for the International Geophysical Year, 1958, at 500 mb over Seattle, Washington. Computations of the yearly mean of the Lagrangian autocorrelation coefficients and eddy diffusivities show that the Lagrangian integral time scale, ·, is equal to 5·0 × 104 sec. It is found that the zonal, x, and meridional, y, components of eddy diffusivity are respectively Kx = 5·90 × 1010 cm2 sec−1 and Ky = 2·30 × 1010 cm2 sec−1. Spectral analysis of the kinetic energy of the Lagrangian geostrophic velocities shows that the kinetic energy densities of both the zonal and meridional components of the geostrophic winds generally increase from high to low frequency with a peak of the meridional component occurring at the frequency of 0·01 cycles hr−1. Analyses are also made of the Eulerian autocorrelation coefficients and energy spectra of the geostrophic velocities. It is found that the Eulerian integral time‐scale, ϵ−1, is equal to 9·4 × 104 sec, making the ratio of the Lagrangian and Eulerian time‐scales near 0·5.
The deepening of wave depressions in relation to geostrophic vorticity advection at 300 mb
Authors: Dixon K. 
Published: February 2007

AbstractIt is found that deepening waves have a characteristic pattern of vorticity advection at the 300 mb level. They have a centre of maximum vorticity advection in the cold air and a marked gradient of vorticity advection extending from this centre across the surface centre of the low into the warm sector. Likewise, non‐deepening and filling waves are also distinctively characterized by their vorticity advection patterns. It is shown that the deepening of waves is related to two parameters, the geostrophic vorticity advection and the scalar product of the gradients of geostrophic vorticity advection and of 300 mb contour height over the centre of the wave. It is further shown that this latter parameter is closely related to the value of the ‘twisting term’ at the level of non‐divergence.
A simple formula for confluent or diffluent currents, with special application to winds
Authors: Groen P. 
Published: February 2007

AbstractIn close formal analogy to the ‘gradient wind’ formula, a formula is derived for confluent or diffluent current (wind) patterns, having only longitudinal accelerations. In first approximation, if the accelerations are not too large, the velocity differs from the geostrophic velocity mainly in direction, the angle of deviation β being determined by:

Where vg = geostrophic velocity, f = 2ω sin ϕ = Coriolis parameter and s = ‘radius of confluence (diffluence)’ or ‘radius of longitudinal acceleration.’
Turbulent energy measurements by vanes
Authors: Maccready P. B. , Jex H. R. 
Published: February 2007

AbstractUtilizing the — 5/3 law spectrum for the inertial subrange of eddy sizes, it is shown that the indicated variance from a direction vane will be the same for an actual vane with a damping ratio of about 0·43 as for a vane with perfect response. For this damping ratio the addition to the variance by overshooting at wavelengths near the natural wavelength compensates for the loss by vane attenuation at shorter wavelengths. the relation between the variance for short sampling times, using such sensors, and ·, the dissipation rate, which represents a basic parameter for inertial subrange eddies, is derived. an airborne method of indicating · continuously is described.
The use of pressure tendencies as an aid to forecasting in east africa
Authors: Sansom H. W. 
Published: February 2007

AbstractIt is shown from the tendency equation that the 3‐hr pressure tendency, corrected for normal diurnal variation, may be an indication of vertical motion. an analysis of twelve months records of weather at both Entebbe and Nairobi confirms the existence of a relationship between pressure tendency and impending weather. the influence of isallobaric convergence on the weather is also demonstrated.
Bearing and incidence of sub‐tropical convective rainfall
Authors: Hudson N. W. 
Published: February 2007

AbstractThe Rose/Farbrother three‐raingauge instrument was used to measure bearing and inclination of rainfall at Mazoe, Southern Rhodesia. Heavy falls of rain (more than 0·5 in.) were found to be associated with small angles of inclination with the vertical. Three‐quarters of the rainfall was from the east and south in the sector 045° to 195°.
Moisture transfer in free and forced convection
Authors: Crawford T. V. 
Published: February 2007

AbstractThe vertical transfer of moisture is examined under conditions where the Richardson number varies from − 2.5 to + 2.9. The use of a non‐dimensional evaporative flux, similar to Priestley's (1959) non‐dimensional sensible heat flux, and extensive data from the Davis lysimeter field show a smooth transition from forced to free convection. An equation for this transitional regime of mixed convection is derived by dimensional analysis and fitted to the data for different Richardson number ranges. A free convection interpretation of the data for −2.5 < Ri < −0.025 gives a proportionality constant of 1.40.In stable conditions, the turbulent transfers are shown to decrease rapidly with increasing + Ri and this behaviour is consistent with some estimates of the initiation of decay of turbulence.
Determination of turbulence dissipation by Eulerian variance analysis
Authors: Frenzen P. 
Published: February 2007

AbstractUsing a ‘variance function’ to specify the variance retained by a time series smoothed via running means, it is shown that the rate of turbulence dissipation can be computed from an Eulerian wind record supplied by a single, 3‐cup anemometer through the relation ϵ = (A) [( ‐)/(Tk2/3 ‐ Tj2/3)]3/2 Here A ≈︁ 3.3 derives from the Kolmogoroff law, Ū is the mean flow, and the numerator of the bracketed term represents the additional reduction in variance effected by increasing the averaging interval from Tj to Tk. Preliminary verifications of the relation are presented, and an experimental programme designed to use the method is outlined.
The electrification of freezing water drops
Authors: Stott Doreen , Hutchinson W. C. A. 
Published: February 2007

AbstractWhen 633 supercooled drops of mean diameter 1.3 mm were nucleated with ice crystals at −1°C and then frozen in air at −15°C the 91 measurable charges on the residues of the 118 drops which broke ranged from −17 × 10−3 to + 25 × 10−3 e.s.u. Spicules were always formed before the drops broke, and in 48 cases the break was across the spicule stem. The breaking spicules containing liquid water resulted mainly in negatively charged residues. Solid spicules usually left positively charged residues. When these results are combined with those of Evans and Hutchinson (1963) the average charge for liquid spicule residues is − 1.4 ± 0.9 × 10−3 e.s.u. (49 drops) and for solid spicules + 3.4 ± 2.2 × 10−3 e.s.u. (25 drops). Other reported observations are also discussed. The magnitudes of the charges are rather high to be explained entirely in terms of the temperature‐gradient theory of Latham and Mason. There appears to be considerable evidence for a charge separation across the boundary between the freezing water and the ice, water being positive and ice negative.
Instability in a geostrophic wind with a transverse wind‐speed gradient
Authors: Wilson S. D. R. 
Published: February 2007

AbstractThe stability of an airstream in geostrophic balance, with a transverse velocity gradient, to horizontal displacements of a single particle has previously been investigated. Here, the effect on such an airstream of a general three‐dimensional disturbance, taking account of the stable density gradient of the air, is considered. A necessary and sufficient condition for instability is obtained for an inviscid airstream and a two‐dimensional disturbance (independent of the downstream coordinate). Finally we discuss how this criterion is modified if viscosity is introduced, and also if the disturbance is allowed to be three‐dimensional.
The description of Australian pressure fields by principal components
Authors: Veitch L. G. 
Published: February 2007

AbstractThe statistical method of principal components, when applied to mean sea level pressure data from the Australian region, shows that, in addition to the well‐known eastward succession of cyclones and anticyclones and the zonal pressure index type of oscillation, an important source of pressure variability is a quasi‐periodic oscillation of pressure over the eastern Australian region, which has ‘periods’ considerably longer than those due to the normal succession of cyclones and anticyclones. These several effects are revealed in the first three principal components which together account for 75 per cent of the total pressure variation.
Cross‐arc deposit of particles from continuous and instantaneous sources
Authors: Walker E. R. 
Published: February 2007

AbstractExperimental details are presented for two series of short‐range diffusion experiments in which glass spheres were emitted from continuous and instantaneous sources. Observed standard deviations of cross‐arc deposits were compared with predictions. For instantaneous sources these standard deviations were fairly well forecast by the simple method of Smith and Hay (1961), although predictions were improved by use of the most appropriate value of β, a Lagrangian‐Eulerian scale factor. Continuous source cross‐arc standard deviations were well forecast by Hay and Pasquill's (1959) method.
A laboratory investigation of the electrification of snowstorms
Authors: Latham J. , Stow C. D. 
Published: February 2007

AbstractArtificial snowstorms were created inside a large cold room by blowing snow crystals over a snow surface. The charges acquired by the visible blown particles and the residual snow surface and the electric fields and concentrations of positive and negative ions produced in the air above the snow surface were measured as a function of the wind velocity, U, the relative humidity, the amount of snow introduced into the air jet, and the temperature of the jet and the snow surface, Tj and Ts respectively; all of these variables were monitored and recorded continuously. In a typical experiment with Tj = − 20°C, Ts = −40°C, U = 430 cm sec−1, and snow crystals introduced into the air jet at a rate of 1 g sec−1 the snow surface acquired a charge of 5 × 103 e.s.u. in 10 sec, the charge residing on the visible blown particles was approximately equal and opposite to this amount, and the concentrations of positive and negative ions created in the air were 4,600 and 4,800 cm−3 respectively, corresponding to a net charge carried on the air within the cold room of less than 1 e.s.u. The charging was found to be a sensitive function of (Tj — Ts) over a very wide range but was independent of Ts except at high temperatures when large‐scale melting and erratic charging were observed. The charging was found to increase rapidly as U was increased from 1 to 5 m sec−1, and was slightly reduced as the relative humidity was raised.The measured electrification at temperatures below 0°C is shown to be entirely explicable, quantitatively and qualitatively, in terms of the temperature‐gradient effect. The charge acquired by the snow surface and the blown particles is a result of fragmentation of snow crystals which have temperature differences across them, asymmetric rubbing between snow particles and transient contact between crystals of different temperatures, all of which processes are manifestations of the temperature‐gradient effect. The primary source of the charge carried by the air is shown to be point discharge between highly charged particles.The contributions to the measured electrification of the Workman‐Reynolds effect, the Dinger‐Gunn effect and the evaporation of ice are shown to be minimal.
The distribution of charge within ice specimens subjected to linear and non‐linear temperature gradients
Authors: Latham J. , Stow C. D. 
Published: February 2007

AbstractNumerical solutions are presented of the differential equations derived by Latham and Mason (1961) describing the distribution of charge within ice specimens across which temperature gradients exist. In the case of specimens subjected to non‐linear temperature gradients the computations predict an extremely rapid increase of volume charge density with increasing temperature gradient and therefore provide an explanation for the reported dependence of the thermo‐electric effect in ice on the geometry of the specimen under investigation.
Evidence of singularities in radiosonde data for Rapid City, South Dakota
Authors: Dennis A. S. 
Published: February 2007

AbstractA search for singularities in the weather at Rapid City, South Dakota is described. It differs from previous investigations of singularities in two respects : (i) the use of pressure and temperature data from radiosondes, and (ii), the application of analysis‐of‐variance techniques to departures of weekly means from fitted annual trends. These analyses lead to the rejection of the hypothesis that there are no weekly singularities in the climatic elements studied. The singularities are tentatively ascribed to week‐to‐week variations in the probability of Arctic outbreaks into the Great Plains region.
Freezing and shattering of supercooled water drops
Authors: Johnson D. A. , Hallett J. 
Published: February 2007

AbstractSupercooled water drops of about 0·05 cm radius were frozen at temperatures between −4°C and −25°C under various conditions. Explosive shattering and ejected ice splinters were observed when supercooled drops were frozen under conditions of free convection in hydrogen and helium at 1·0 atm pressure, in air below 0·13 atm pressure and in carbon dioxide below 0·05 atm pressure. Drops did not fracture when ventilated at terminal velocity unless they were rotated about an axis normal to the airstream during freezing. Fracture was also observed when either the drops were not allowed sufficient time to attain thermal and solution equilibrium with the environment before nucleation, or when drops were frozen in carbon dioxide at a pressure above 0·3 atm.A condition for drop fracture is the establishment of a strong shell of ice around the drop, which in turn depends on the distribution of heat transfer to the environment during freezing and on the effective thermal conductivity of the environment. The volume of gas dissolved in the drop is a secondary factor, except in the case of a very soluble gas such as carbon dioxide where splinters are produced by vigorous effervescence during freezing. In the atmosphere the shattering of an individual drop appears possible only if the drop rotates during freezing. This appears unlikely since any asymmetry in shape would tend to orient the drop as it fell.
The spectra of charging events due to the collision of natural ice particles with an ice surface
Authors: Scott W. D. , Hobbs P. V. 
Published: February 2007

AbstractA sensitive, solid state electrometer has been built which is capable of measuring the individual charges acquired by an ice surface exposed to precipitation or cloud particles. Measurements made in natural snowfall show that the individual charges fluctuate widely both in sign and magnitude. Individual charges ranging from ‐10−2 e.s.u. to 10−2 e.s.u. have been recorded within an interval of a few seconds. In most cases the ice surface received a net positive charge, and the median charge per collision was about 2 × 10−4 e.s.u. The charging spectra commonly followed a log‐normal distribution.It is suggested that two important mechanisms for the charging were the direct transfer to the ice surface of some of the charge residing on the ice particles in the air and the fragmentation of the ice particles as they collided with the ice surface.