bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some characteristics of stratiform clouds over North Ireland in relation to their precipitation
Authors: Mason B. J. , Howorth B. P. 
Published: February 2007

AbstractAnalysis of stratiform‐cloud data from routine aircraft ascents made at Aldergrove during 1942‐4 and of ground‐station records of precipitation reveals that drizzle fell predominantly from clouds warmer than −5°C and thicker than 600 m, suggesting growth of drops by coalescence. Rain fell occasionally from clouds not extending above the −5°C level but fell mainly from clouds with tops colder than −12°C suggesting that ice crystals were mainly responsible for its release. The frequency and persistence of precipitation are analysed with respect to the temperature structure and the depth of the clouds. Some differences between the characteristics of precipitating and non‐precipitating clouds are brought out.
On the generation of charge associated with graupel formation in thunderstorms
Authors: Mason B. J. 
Published: February 2007

AbstractIt is argued that the generation and separation of electric charge above the 0°C level in thunderclouds are consequences of the growth and fall‐motion of graupel pellets. The results of laboratory experiments which show the acquisition of a negative charge by a growing rime deposit are used to calculate the charge liberated during the growth, in a thunderstorm cell, of ice particles by the accretion of supercooled cloud droplets. The calculations show that, in a vigorous warm cumulonimbus, it is possible for this process to generate about 1,000 C of charge within about 11 min of the activation of ice nuclei at the −10°C level, and that this volume of charge can be subsequently separated by the falling precipitation elements at a rate which can account for the production of several successive lightning flashes over a period of a few minutes.
The sampling of rain and cloud drops using hygrophotographic plates covered with various kinds of oil
Authors: Sivadjian Joseph 
Published: February 2007

AbstractThe preparation of a hygrophotographic plate is described, gives excellent results in the sampling of cloud droplets, when the latter have diameters between 20 and 30 μ. To avoid the shattering of larger drops (100 to 200 μ) the plate should be smeared with a layer of castor oil. The droplets of water, owing to their density being greater than that of the oil, sink to the bottom of the oily film, are immediately absorbed by the gelatine and thus are recorded.
A direct measurement of infra‐red radiation divergence to 160 mb
Authors: Suomi V. E. , Staley D. O. , Kuhn P. M. 
Published: February 2007

AbstractA simple, economical balloon‐borne net radiometer is described. The net radiation is essentially obtained from the difference of fourth‐powers of the temperatures of the bottom and top radiating surfaces, and the internal conduction, which is proportional to the temperature difference between the bottom and top surfaces. The results of a measurement of net radiation to 160 mb are discussed.
The convective regime and temperature distribution above a horizontal heated surface
Authors: Croft J. F. 
Published: February 2007

AbstractThe convective flow and temperature distribution above a horizontal heated surface in air have been examined by optical methods. Attention has been given both to the open system and to enclosed air layers. The observations show the existence close to the surface of a mode of convection similar to the cellular convective motion previously noted in shallow enclosed layers. This motion is found to be present both in the open system and in the lower part of an enclosed layer of wide separation, i.e., large Rayleigh number.The mean temperature profile in this region has been found for a range of surface temperatures and the results show that the logarithm of the mean absolute temperature (T) varies as the power (−1/2) of the height (Z) above the heated surface. This measured distribution has been compared with theoretical predictions in particular that of the Priestley similarity theory, which properly refers to convection above an infinite surface and in which the postulated conditions will apply more exactly in higher layers. Nevertheless the measured temperature profile in the surface region is of the form predicted by the Priestley theory with the experimental value (−1/2) in place of the theoretical (−1/3) as the power of the height (Z).
Solar radiation and the duration of sunshine in Trinidad, West Indies
Authors: Smith G. W. 
Published: February 2007

AbstractRecords of daily solar radiation energy extending over a period of one year have been compared with readings of sunlight duration obtained with a Campbell‐Stokes recorder. Energy records were made with a bimetallic antinograph. The regression equation obtained for the daily values in Trinidad, West Indies was R = RA (0·20 + 0·59 n/N), with a correlation coefficient of 0·91 where R = radiation actually receivedRA = Angot's theoretical amounts of radiation which would reach the earth's surface in the absence of an atmosphere. These values are given by List (1951)n = actual duration of sunlightN = theoretical maximum duration of sunlight.
Size‐distribution of ice crystals in cumulonimbus clouds
Authors: Jones R. F. 
Published: February 2007

AbstractIce‐crystal size‐distributions have been measured in clouds associated with the intertropical convergence zone and more isolated cumulonimbus clouds in temperate zones. Mean size‐distributions fit curves ND = 1,000/D3 and ND = 1,000/D2·3 in tropical and temperate clouds respectively where ND δD is the number per m3 with diameters between D and D + δD mm. The tropical curve is a close fit throughout the measured range of D (0·05 to 4 mm) but the temperate curve is applicable in the range up to D = 2 mm only, there‐after a curve ND = 10,000/D5·4 fits the curve for D = 2 to 5 mm. In temperate clouds there is little variability with temperature except for a decrease in size of the largest particles observed as temperature decreases.There is some evidence that the particles caught are graupel of mean density 0·6 g cm−3 and, on this assumption, variation with total ice‐crystal concentration suggests an empirical distribution law for particles with diameters 0·25 mm or greater of \documentclass{article}\pagestyle{empty}\begin{document}$ N_D = 10^{4.1} \exp [ - \frac{{2.67}}{{W^{\frac{1}{3}} }}(D - 0.25)] $\end{document} where W is the ice‐crystal content in g m−3.
A surface energy‐balance computer
Authors: House G. J. , Rider N. E. , Tugwell C. P. 
Published: February 2007

AbstractA surface energy‐balance computer is described. This is fed with such information as dry‐ and wet‐bulb temperatures and temperature differences in the vertical (in the form of fine wire thermocouple outputs) and wind speed differences. The psychrometric equation is solved automatically to yield a vapour‐pressure difference and the latent‐heat term is then computed on the basis of an aerodynamic equation. The sensible‐heat term is similarly made available. The net flux of radiation and the soil‐heat flux are also recorded. A determination of each of these four fluxes is made once per minute and the values are integrated and presented on counters which are photographed at desired intervals, the smallest interval so far used being 20 min. Results indicate that for periods of an hour or more the ‘positive’ and ‘negative’ terms in the surface‐heat balance equation so obtained, agree to about 10 per cent except when the heat storage in the first two cm of soil, of which no account is taken, is obviously changing. The only complete 24 hr observational period so far covered indicates a daily balance to a fraction of a mw hr cm−2. Over approximately 80 hr observations, which were not continuous but contained about an equal number of daylight and dark hours, a balance to better than 1 per cent was obtained. A further result, which requires additional confirmation, is that the daily water loss from the centre of an extensive short‐grass area which has an ample water supply may be obtained for all practical purposes by measuring the total net radiation and assuming that all is used in the evaporative process. It becomes obvious that if hourly mean values of the profiles of temperature, humidity and wind are used to compute the evaporation then, in general, the results will be in error by up to about 20 per cent, although daily totals may be more accurate than this. The machine as it stands is not reliable for continuous operation owing to the use of a number of electro‐mechanical devices which are required to work under conditions for which they were not designed. Some improvements will be required before reliable continuous operation becomes possible.
A determinant hypothesis for the superadiabatic wind and temperature profiles
Authors: Priestley C. H. B. 
Published: February 2007

AbstractThe view is advanced that values of the Monin‐Obukhov coefficients, as they are obtained from field data, are products of smoothing rather than true physical constants of a steady regime intermediate between free and forced convection. This hypothesis provides a satisfactory prediction of the first coefficient and, if it is correct, reduces the dual problem of heat and momentum transfer in superadiabatic conditions to the specification of four constants : von Kármán's constant, Priestley's free convection constant, and the ratio KH/KM in neutral and in free convection conditions.In inversion conditions it has yet to be shown whether the constancy of stress and heat flux extend very far, if at all, above the level where significant departures from the neutral profile begin. Thus the basic assumption of some common current approaches still awaits examination.
Airflow in convective storms
Authors: Browning K. A. , Ludlam F. H. 
Published: February 2007

AbstractSome known properties of travelling storms are used to infer a general model of the airflow within them, in which updraught and precipitation‐maintained downdraught are fed persistently from opposite sides. Detailed radar and ground observations of a particular hailstorm are used to refine the model.
Measurements of solar ultraviolet radiation in the stratosphere
Authors: Brewer A. W. , Wilson A. W. 
Published: February 2007

AbstractIn order to improve the accuracy of the fundamental data required for calculations of the photo‐chemical production of ozone, the intensity of the solar ultraviolet light, λ ≈︁ 2100 Å, which penetrates to the lower stratosphere, has been measured with the sun directly overhead. The radiation was first detected at the 196 mb level where the flux was 2 × 108 photons cm−2 sec−1 and two of three ascents reached the 6 mb level where the flux was 1.2 × 1013 ph cm−2 sec−1. The results of calculations of the expected intensity at different levels are also presented and adjustments to the data used are found to be necessary in order to obtain agreement with the measurements.
The capture of airborne particles by water drops and simulated snow crystals
Authors: Starr J. R. , Mason B. J. 
Published: February 2007

AbstractCollection efficiencies of falling water drops ranging from 1/10 to 1 mm in radius for spores of Lycoperdon (mean radius r = 2.25 μ), spores of black rust (r = 2.6 μ), and grains of Paper Mulberry pollen (r = 6.4 μ) have been determined. The experimental results are in fair agreement with calculations based on the assumption of potential flow around the larger drops. With both kinds of small spore the collection efficiencies reach maximum values for drops of about 400 μ radius and fall sharply for smaller drops. In this latter regime, where the potential flow solution is inappropriate and the viscous flow solution gives zero values, a sharp fall in collection efficiency is to be expected. Aggregates of two or three spores are collected slightly more efficiently than single spores, but the results show very similar trends in all cases.Some preliminary results have been obtained on the collection of pollen grains by circular, hexagonal and star‐shaped paper discs that simulate snow crystals. The collection efficiencies, as deduced from the numbers of particles caught on their leading faces, are usually < 0.05, but the appearance of similar numbers of particles on the trailing faces suggests that particle capture in the wake of the disc is important at these Reynolds numbers of about 100.
Specification of sea‐level pressure from 700‐mb height
Authors: Klein W. H. 
Published: February 2007

AbstractAn objective method of translating a map of 700‐mb height into its accompanying chart of sea‐level pressure is derived by applying the screening regression technique to 17 years of synoptic data at 469 grid points covering the Northern Hemisphere for every other month of the year. On the average the regression equations explain almost 70 per cent of the pressure variance by means of approximately 3 heights and have a standard error of estimate of about 4 mb. The variation of these properties with geography, latitude, and month is illustrated and discussed. Valuable climatological material is also presented on the standard deviation of daily 700‐mb height and sea‐level pressure and the correlation between these variables.The equations have been programmed for the electronic computer so that automatic, curve‐followed, and hemispheric sea‐level pressure maps can be produced in a few minutes. The programme has been applied to numerical prognostic heights prepared in the National Meteorological Center. The resulting objective forecasts of the sea‐level pressure field are illustrated and compared with predictions produced by other methods.
Absorption and emission by carbon‐dioxide in the mesosphere
Authors: Houghton J. T. 
Published: February 2007

AbstractTheoretical and experimental evidence is presented which leads to a vibrational relaxation time appropriate for the v2 vibration of CO2 at 15 μ under atmospheric conditions at 210°K and standard pressure of 6·0 × 10−6sec. The effect of this on the atmospheric cooling rate near 90 km due to emission by CO2 is discussed. It is shown that absorption of solar radiation by the v3 band (at 4·3 μ) and the combination bands of CO2 (at 2·7 μ) leads to a heating rate of about 2°C (12 hr)−1 near 80 km, this being one of the largest contributions to the radiative heating rate at this altitude. The processes by which relaxation from the v3 vibration of CO2 occurs involve vibrationally excited oxygen and the v2 vibration of H2O. The magnitude of heating‐rate depends considerably, therefore, on the H2O concentration. For thermal radiative exchange by the v3 band, thermodynamic equilibrium begins to break down at 30 km; its contribution to the radiative budget of the mesosphere is consequently very small.
General and special approaches to the problem of objective analysis of meteorological variables
Authors: Kruger H. B. 
Published: February 2007

AbstractA general formulation of the problem of objective analysis by computer consists of a simple equation in which the value of a meteorological variable at a given grid point is expressed in terms of three components which together include all potential ingredients. Several specialized analysis equations associated with existing schemes are obtained from the general equation, and the relevant methods of specifying weights are outlined. These methods were evaluated by performing a 500 mb height analysis using ‘perfect’ data and the same trial field with each. The best relative results were obtained when weights were determined by solving a system of linear equations involving weight parameters based on the autocovariances of observed minus trial values (residuals). A consideration of conditioning problems suggests that the choice of weight parameter should be appropriate to the manner in which the trial value at the grid point is synthesized. The implications of the investigation are that an optimum method of analysis should take into account data type, quality, distribution, predictability, prediction reliability and a statistical or empirical evaluation of the structure of the meteorological field about every grid point.
Divergence measurements from an aircraft
Authors: Axford D. N. 
Published: February 2007

AbstractA comparison between the changes in wind calculated from Doppler data and from an inertial system shows that variations in Doppler winds of over five knots may be caused by small changes of heading and air speed. The accuracy of average winds over a ten minute period is thought to be better than five or six kt.A 500 mb wind field has been measured across a 50 nm square centred on the Scilly Isles and a value for the divergence out of the square has been calculated from the wind measurements. The accuracy of this measurement is estimated to be ± 3 × 10−5 sec−1.
Air motion and precipitation growth in a wave depression
Authors: Browning K. A. , Harrold T. W. 
Published: February 2007

AbstractA case study is presented to illustrate the small and medium scale air motion and precipitation patterns within a travelling wave depression. Air motion has been studied by means of isentropic and Doppler radar analyses; precipitation patterns have been studied by means of meso‐analysis of autographic rate‐of‐rainfall records and conventional 3‐dimensional radar data. The results confirm and elaborate upon earlier studies in which precipitation generation is classified according to whether it is due to large‐scale ascent alone or is modified by vertical instability. The influence of orography is also discussed.
Comparison of turbulent fluxes over water determined by profile and eddy correlation techniques
Authors: Miyake M. , Donelan M. , McBean G. , Paulson C. , Badgley F. , Leavitt E. 
Published: February 2007

AbstractThe turbulent fluxes of momentum and heat were determined by the eddy correlation and profile techniques for over water, fetch limited, near neutral conditions. The estimates agree well within the experimental error. The ø11 technique estimates of stress are systematically higher.
Ozone behaviour associated with the middle stratospheric circulation during the southern spring of 1967
Authors: Pittock A. B. 
Published: February 2007

AbstractLarge changes in the temperature and ozone content of the stratosphere at Aspendale (38 S, 145 E), Hobart (43 S, 148 E) and Macquarie Island (54 S, 160 E) are associated with the passage of planetary waves in the Antarctic polar vortex. Application of the conservation equation to an elliptical model of the polar vortex, using both ozone and potential temperature as tracers, leads to order of magnitude estimates of the vertical and horizontal motions and transports involved. Estimated vertical motions are of the order of 1 cm s−1. At the 30‐mb level there is significant horizontal advection of ozone into the vortex in the vicinity of the cold troughs and out of the vortex near the ridges, but horizontal advection of heat appears to be negligible.
A wind tunnel investigation of the internal circulation and shape of water drops falling at terminal velocity in air
Authors: Pruppacher H. R. , Beard K. V. 
Published: February 2007

AbstractThe internal circulation and the shape of water drops falling at terminal velocity in air of 20°C at sea level pressure, and nearly water saturated, were studied by means of a wind tunnel. Drops with an equivalent radius a0 smaller than 140 üm had within the experimental error no detectable deformation from spherical shape. Drops of sizes 140 μm ≤ a0 ≤ 500 μm were slightly deformed into an oblate spheroid. The deviation of these drops from spherical shape was found to be in fair agreement with that theoretically predicted by Imai (1950) and others. The deformation of drops of sizes 0.5 mm < a0 < 4.5 mm was found to be linearly related to the drop size. Such a linear relationship is predicted by the semi‐empirical calculations of Savic (1953).By means of a tracer technique it was established that water drops falling at terminal velocity in air have a well developed internal circulation. The flow pattern inside a drop was found to be consistent with the flow pattern of the air around the drop and that predicted theoretically by Hadamard (1911) and by Hamielec and Johnson (1962). The surface velocity at the equator of a drop was found to be about 1/100 of the drop's terminal velocity. The experimentally determined internal velocities were compared with those predicted theoretically by McDonald (1954) from boundary layer theory and by Hadamard (1911) based on Stokes flow.
The influence of nitrogen oxides on the atmospheric ozone content
Authors: Crutzen P. J. 
Published: February 2007

AbstractThe probable importance of NO and NO2 in controlling the ozone concentrations and production rates in the stratosphere is pointed out. Observations on and determinations of nitric acid concentrations in the stratosphere by Murcray, Kyle, Murcray and Williams (1968) and Rhine, Tubbs and Dudley Williams (1969) support the high NO and NO2 concentrations indicated by Bates and Hays (1967).Some processes which may lead to production of nitric acid are discussed.The importance of O (1S), possibly produced in the ozone photolysis below 2340 Å, on the ozone photochemistry is mentioned.
Air motion and precipitation growth at a cold front
Authors: Browning K. A. , Harrold T. W. 
Published: February 2007

AbstractA case study of a cold front has shown that, although appreciable ascent occurred over a deep layer, practically all precipitation growth was associated with the ascent of air which originated within the friction layer ahead of the front. Doppler radar observations showed that the ascent was accomplished in two phases; first through near‐vertical line convection to between 1 and 3 km at the surface cold front, and thence through shallow‐slope convection of the same air to between 3 and 6 km. The line convection was 2‐dimensional rather than cellular and occurred in the absence of appreciable hydrostatic instability. Horizontal convergence at low levels was very intense (10−2 s−1 averaged over 500 m vertically and horizontally), so that despite the shallowness of the line convection, the updraught attained a rising speed of 8 m s−1 which was sufficient to generate hail and thunder. The subsequent slope convection produced a period of moderate precipitation behind the surface cold front, and was associated with a pronounced transverse circulation, with strong gradients of velocity separating the weak downdraughts in (and beneath) the sloping frontal zone from the overlying updraught. The overall efficiency of precipitation production was high, 60 per cent of the water vapour flux in the rising air reaching the ground as precipitation.
Numeric calculation of turbulent diffusion
Authors: Thompson R. 
Published: February 2007

AbstractA simple, flexible method involving a random number generator is given for simulating time dependent dispersion. The diffusion is simulated by letting a series of particles move with the local mean wind plus random fluctuations of this wind. This simulation method is not greatly complicated by introduction of horizontal and vertical shear, buoyancy, or anisotropic turbulence, and generally requires less computer time and storage than needed for finite difference computations of comparable accuracy over a network of fixed grid points. Solutions of particular cases compare well with known solutions.
Hysteresis effects in a differentially heated rotating fluid annulus
Authors: Cole R. J. 
Published: February 2007

AbstractThis paper is concerned with the motion of an annulus of fluid which is contained between two cylinders rotating about their common axis. The fluid is differentially heated in the horizontal. Examination of the stability of the wave régime flow is carried out by perturbing an averaged form of a non‐linear wave‐régime solution. This leads to a linear system describing the disturbance and is solved approximately using a truncated Fourier series. By this means theoretical stability criteria are obtained in terms of the Rossby number and the wave number. These results are compared with experimental wave change criteria and qualitative agreement is found.