bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of stability on computed tendencies and vertical velocities
Authors: Knighting E. , Gilchrist A. 
Published: February 2007

AbstractThe two‐parameter models used in numerical prediction of the contour height field usually assume a constant value of the hydrostatic stability, about −0·04°C mb−1. The effect of varying this value over the field is investigated and it is shown that as the stability approaches zero the computed tendencies and the vertical velocities are increased.
Snowfall measurements in northern Canada
Authors: Jackson G. I. 
Published: February 2007

AbstractSources of error in Canadian snowfall records are discussed, with particular reference to the six‐hour interval between measurements. Very slow rates of fall are usual at high latitudes and these cause ‘traces’ of snow to be recorded frequently which are not included in precipitation totals. Experience on Ellesmere Island suggests that the contribution from these traces may form a high proportion of total winter snowfall, and a longer interval between measurements seems desirable.
Radar scatter by large hail
Authors: Atlas D. , Harper W. G. , Ludlam F. H. , MacKlin W. C. 
Published: February 2007

AbstractRadars with wavelengths of 3·3 and 4·67 cm have been used to measure the back‐scatter cross‐sections of individual artificial hailstones and their variations as melting occurs. The measurements confirm the cross‐sections computed theoretically. An ice sphere is a better scatterer than a liquid water sphere of equal size when its diameter exceeds 0·8 wavelengths; when the diameter lies between 1·2 and 2·3 wavelengths it is better by a factor of 10 or more. This behaviour of ice is supported by scatter measurements on a set of plexiglass (perspex) spheres with refractive index close to that of ice.When melting begins, the 3·3 cm cross‐sections drop sharply toward the all‐liquid values; those at 4·67 cm decrease gradually, and sometimes not at all. The rate of decrease of the cross‐sections during melting is also more variable at 4·67 cm than at 3·3 cm. Most of the 3·3 cm change appears to occur during the initial growth of the liquid coat to a maximum thickness of about 0·01 cm, while the major drop in 4·67 cm cross‐sections occurs well beyond this stage of melting. The implications are that: (1) a water coat of 0·01 cm thickness has a major effect at 3·3 cm and a minor one at 4·67 cm; (2) liquid continues to collect in subsurface cracks and cavities in the ice and causes a further decrease in the cross‐sections after the maximum thickness of water coat has formed. The final cross‐sections are generally within 2 db of the all‐liquid value after 7 to 10 minutes of melting at 3·3 cm and after 15 to 20 minutes at 4·67 cm. Possible reasons for these results are discussed.
Measurements on the electricity of precipitation
Authors: Ramsay M. W. , Chalmers J. Alan 
Published: February 2007

AbstractMeasurements have been made of the electricity of precipitation, the potential gradient and the rate of rainfall. The results for the winter of 1957/58 show general agreement with those of earlier workers, in giving a linear relation between potential gradient and precipitation current, but those of the summer of 1958 are less crdered. Comparisons have been made of the currents to open and shielded receivers, and show general agreement. The ‘mirror‐image effect’ and time delays connected with it have also been studied, without any complete explanation.
Satellite cloud pictures of a cyclone over the Atlantic Ocean
Authors: Fritz S. 
Published: February 2007

AbstractA composite of Tiros 1 pictures describing the cloud system in a mature cyclone, centred in the Atlantic Ocean to the west of Ireland, is described. Comparison of the pictures with conventional meteorological data shows that a stratiform cloud surrounding the storm was identical in position with a warm moist tongue of air flowing around the storm. In the centre of the storm where the clouds were more broken, giving the appearance of cumuliform clouds, a large mass of cold, dry air extended from the surface up to the tropopause above 400mb. A few areas of steady precipitation were present in the stratiform cloud regions while more scattered showers existed in the central cumuliform region. An area of relatively high winds circled the storm, in conformity with the expectations from the thermal wind relation when cold air and warm air layers reside side by side. A brief comparison is made between the vertical motion computations based on conventional data and the cloud areas.
The absorption of solar radiation by water vapour and carbon dioxide in a cloudless atmosphere
Authors: Roach W. T. 
Published: February 2007

AbstractA method of computation of the direct absorption of solar radiation by the near infra‐red bands of water vapour and carbon dioxide in a cloudless, non‐scattering atmosphere using recent laboratory data compiled by Howard, Burch and Williams (1955) is described.Three applications of this computation are discussed:(i) Heating rates in an atmosphere whose water‐vapour distribution is given by radiosonde or aircraft observations.(ii) Instantaneous heating rates as a function of solar zenith angle, altitude and precipitable water vapour.(iii) A climatological study of heating rates in a cloudless atmosphere integrated over a 24‐hr period as a function of latitude, season, altitude and precipitable water vapour. The relative contributions to heating by water vapour and carbon dioxide are assessed between 10 and 1,000 mb.The mixing ratio of carbon dioxide was assumed constant throughout the atmosphere, while idealized vertical distributions of water vapour mixing ratio were used in (ii) and (iii).
Accretion in mixed clouds
Authors: Macklin W. C. 
Published: February 2007

AbstractAn object on which ice is deposited when it moves through a supercooled cloud is warmer than its environment owing to the release of heat of fusion. If the rate of accretion is sufficiently great, the temperature of the object is raised to 0°C and its surface becomes wet. It has often been assumed that water in excess of that which can be frozen is shed into the wake of the object. The present experiments show that, at temperatures below – 2°C, the excess water is not shed but is incorporated into the ice structure, giving a ‘spongy’ deposit. Even in the temperature range – 2 to 0°C, the excess water can be retained if a sufficient concentration of ice particles is introduced into the droplet cloud. It has also been found that over a wide range of conditions, considerable quantities of ice particles may be accreted in addition to the supercooled droplets, and the crystalline structure of the deposit is modified accordingly. It is considered that at temperatures near 0°C, and possibly at lower temperatures the presence of ice particles in the supercooled cloud is necessary in order that none of the unfrozen water is shed.The restriction formerly thought to be imposed on the growth rate of hailstones in the wet condition may now be removed.
Total ozone and perturbations in the middle stratosphere
Authors: Boville B. W. , Hare F. K. 
Published: February 2007

AbstractTotal ozone amounts are shown to vary with the motion systems of the stratospheric polar vortex. Two cold outbreaks, one over Europe in 1959 and the other over North America in 1960, produced similar pronounced minima in the total ozone records. The results support the hypothesis that major anomalies in the horizontal and seasonal distributions of total ozone are related to dynamical activity in the polar‐night vortex and the stratospheric warm belt.
Multi‐wavelength radar reflectivity of hailstorms
Authors: Atlas D. , Ludlam F. H. 
Published: February 2007

AbstractComputations are made of the radar reflectivity Ze of particles present in hailstorm updraughts in exponential size spectra. The reflectivity varies substantially according to the radar wavelength and according to whether the particles are wet or dry. In severe storms a very strong echo may be observed aloft. Partly by reference to a particular example it is shown that its magnitude at the shorter wavelengths (Ze ± 107 mm6 m–3), and the variation of its intensity with wavelength, can reasonably be explained only if the responsible particles are large dry hailstones of almost uniform size. The dryness and sorting of the large stones is attributed to fall outside the updraught through a wind shear, and the decrease of echo intensity lower down to their re‐entry into the updraught and wetting. It appears that the likelihood and size of hail at the ground are indicated by echo intensity aloft at 3 cm, and less sensitively at 4·7 cm, but not at 10 cm. Measurements of echo intensity at several wavelengths are helpful in the study of severe storms.
Radiative transfer in the lower stratosphere due to the 9.6 micron band of ozone
Authors: Hitschfeld W. , Houghton J. T. 
Published: February 2007

AbstractPrecise numerical calculations of the flux divergence due to narrow regions of the ozone 9.6 micron band were made, using the relative strengths and positions of the spectral lines calculated by Kaplan, Migeotte and Neven (1956). The absolute line strength was estimated on the basis of Walshaw's (1957) laboratory measurements. Spectral models or Curtis's approximation were not used, but Lorentz shapes and uniform widths were assumed for all lines. Calculations up to a height of 33 km were made for two ozone ascents of Brewer and Milford (1960). The atmospheric heating rates obtained for narrow regions of the band were then combined to estimate the heating rate by the whole band with results in qualitative agreement with, though nearly twice as great as those of Plass (1956a). The effect of the radiative temperature of the atmosphere below the ozone layer (whether of ground or cloud top) appears to be great. The radiative heating by ozone in the 10‐20 km region is 0·2 or 0·3 degrees C per day for a ground temperature of 10°C, but may disappear altogether, if cloud is present just below the tropopause.Using a larger computer, the procedure could be extended to cover the whole band, thereby avoiding the approximate extrapolation employed in this paper. The procedure could be applied to any absorption band, and is flexible to permit the use of any desired pressure and temperature dependence of the shape, width and strength of the spectral lines; results from it might serve as a standard against which conclusions reached by approximate methods can be checked.
Wind profiles over hills (in relation to wind‐power utilization)
Authors: Frenkiel J. 
Published: February 2007

AbstractFollowing a previous country‐wide wind survey, two sites – each typical of one of the following two topographical categories: (a) a hill forming a part of a mountain ridge athwart the prevailing wind direction with steep leeward slopes, and (b) an isolated peak in a valley in the general direction of prevailing winds – were chosen for detailed investigation of wind behaviour with the purpose of correlating the characteristics of the wind flow over the hill to its topography. At each site, wind vertical gradient, wind direction, and temperature vertical gradient were measured in the height interval of interest to wind‐power utilization (10 m to 40 m above the hilltop) for a period of about a year.These measurements have shown:

There is no close relationship between mean wind profile and mean temperature profile over hills.
Whilst the directional wind profiles are practically uninfluenced by wind speed, they are largely determined by: (a) the hill profile in the immediate neighbourhood of the site of measurements, and (b) the hill profile further upwind in relation to that near the measurements site.
The effect of thermal stratification is important for all wind speeds with the curves of wind ratio as a function of temperature gradient exhibiting a both minimum and a maximum, the location of which on the scale of temperature gradient depending on the hill profile.
A classification of wind‐power sites is given based on a single criterion, i.e., mean wind vertical gradient for the height interval from 10 m to 40 m. For optimal conditions for wind‐power utilization this gradient must vanish, a flow condition resulting from: (a) small hilltop area; (b) regular and smooth slopes of about 1 in 3 1/2 in the nearest few hundred metres from the hilltop.
Two‐dimensional mountain waves – a method for the rapid computation of lee wavelengths and vertical velocities
Authors: Foldvik A. 
Published: February 2007

AbstractLee wavelengths and vertical velocities have been computed for twenty‐six airstreams where reliable observations of the wave motion behind mountain ridges are available. The actual distribution of wind and stability has been modified in each case in order to approximate the internal parameter in the lee‐wave equation by an exponential function, as recommended by Palm and Foldvik (1960). There is good accordance between the computed wave motion and the observations.
The rise of an isolated thermal in wind shear
Authors: Hall W. S. 
Published: February 2007

AbstractUsing formulae derived by dimensional analysis from experiments on thermals in still surroundings, a theory is built up which predicts the motion of a thermal rising in various wind shears. A criterion to give the limits of applicability of the theory is put forward. Finally, the theory is applied to calculating the coefficients of heat and momentum transfer, where transfer is due solely to the rise of thermals.
On the balance of forces and radial accelerations in hurricanes
Authors: Gray W. M. 
Published: February 2007

AbstractThe degree to which the gradient or cyclostrophic wind equation is applicable for hurricane winds above the surface friction layer is tested on 10 levels in four hurricanes (8 different days) in which aircraft of the National Hurricane Research Project of the United States Weather Bureau flew radial leg penetrations during the 1957–58 seasons. All 10 levels flown were between 6,000 and 16,000 ft altitude and each level had six or more radial leg penetrations except one that had five. Application of the cylindrical radial equation of motion is made for the constant‐pressure levels flown. Results show that there is lack of radial balance by a wide margin between pressure gradient, centrifugal and Coriolis forces. Evaluation of the local and advective changes of the substantial derivative only partly makes up for this lack of balance. It is therefore necessary to postulate the existence of internal radial friction, both in an instantaneous fixed‐coordinate system and in one that moves with the storm centre. This residual radial friction averages 25 to 30 per cent of the pressure‐gradient force. As a consequence, the gradient wind equation in both cyclindrical and in natural coordinates is invalid. Also, steady‐state or deepening hurricanes must have stronger pressure gradients than corresponding centrifugal and Coriolis accelerations. Comments on the possible mechanism for this internal friction are given.
Pressure oscillations and fallout downdraughts
Authors: Clarke R. H. 
Published: February 2007

AbstractThe generation of widespread pressure oscillations in southern Australia on 26–27 January 1960 is examined in some detail, by means of available barograms, and spectral analysis of a Melbourne Dines microbarogram. Photographs of mamma cloud taken at Adelaide give some insight into the processes at work producing both cloud form and oscillations. It is concluded that the oscillations were due to wave motions on an interface with large density contrast, at about 1,500 m altitude, and that these motions propagated approximately in the direction of vertical shear, with the velocity of the wind at about 2·5 km. Their phase and group velocities were similar, and their wavelengths in the range 10–70 km. These waves appear to have been transmitted over great distances without marked attenuation. An estimate of the energy of oscillation was compared with that which could be imparted to a horizontal interface with strong shear by the passage of downdraughts through it, and the conclusion is reached that the combination of downdraughts and shear could have provided the energy. On the other hand, there is good evidence that the waves were unstable, and could therefore have drawn their energy from that of the mean motion. Examination of other occasions on which marked pressure oscillations occurred suggested that fallout and strong shear were both necessary conditions.
Comparison of ozone variations and of its distribution with height over middle latitudes of the two hemispheres
Authors: Kulkarni R. N. 
Published: February 2007

AbstractThe paper contains a study of the day‐to‐day, seasonal and latitudinal distribution of ozone over the southern hemisphere in comparison with those observed in the northern hemisphere. It has been observed that there is more ozone over the middle latitudes of the southern hemisphere in summer, autumn and early winter, than in the northern hemisphere, whereas the spring maximum values are more or less the same in both hemispheres, suggesting lesser destruction of ozone from spring to autumn in the southern than in the northern hemisphere.The distribution of ozone with height computed from umkehr observations over Aspendale by method B has been compared with that over Tateno in Japan. The results are discussed in relation to the idea of a poleward flow of air from the lower stratosphere and the neighbourhood of the equatorial tropopause in the southern hemisphere. It is concluded that the mean meridional circulation in the lower stratosphere of the southern hemisphere is weaker than, or at any rate only as vigorous as that in the northern hemisphere in spring.
The chemical composition of precipitation at cloud levels
Authors: Oddie B. C. V. 
Published: February 2007

AbstractIn an attempt to obtain precipitation samples free from contamination either from industrial sources or from sea spray, samples were collected by an aircraft of the Meteorological Research Flight over Southern England at heights up to 8,500 ft. Most of the samples still showed clear evidence of industrial pollution: however, five of them were collected under synoptic conditions which render pollution improbable. The amount of dissolved matter in these samples is much smaller than in the remainder, and their composition shows a close similarity with that of samples collected at ground level in regions where pollution is slight. It is considered likely that the solute has been little affected by matter derived directly from land : but it still shows characteristic differences from sea‐salt, particularly in the much smaller proportions of sodium and chlorine in comparison with all other elements. It is suggested that these differences must arise from some reaction, occurring either at the sea surface or in the atmosphere itself, but there is insufficient evidence to determine its nature.
On the formation of spongy ice
Authors: Macklin W. C. , Ryan B. F. 
Published: February 2007

AbstractIn supercooled water at temperatures down to‐4·5°C, ice grows in the form of flat dendritic sheets. Between‐4·5° and −5°C a transition in the manner of freezing occurs and three‐dimensional ice structures are produced. At temperatures below‐5·5°C this results in a structure which retains liquid water and so gives rise to spongy ice.
Heat transfer from hailstones
Authors: Macklin W. C. 
Published: February 2007

AbstractBy measuring the rate of melting of spheres and oblate spheroids of ice in an airstream, the dependence of the rate of heat transfer on shape has been determined. Applying the results to hailstones, it has been found that, in terms of the maximum dimensions of the stones, melting is more pronounced as the ratio of the minor to major axes decreases. Melting also causes the stones to become more oblate. The critical liquid‐water concentrations of spheroidal hailstones have been deduced from the experimental data and, for stones of the same maximum dimension, are dependent of the axis ratio. It is further shown that the updraught profiles required to grow spheroidal hailstones at the just‐wet condition are not much different from those required for spherical stones.
Note on the measurement of ozone in the atmosphere
Authors: Dobson G. M. B. 
Published: February 2007

AbstractThe absorption coefficients of ozone for ultra‐violet wavelengths which have previously been accepted as correct, do not agree with measurements made on the ozone in the atmosphere. New laboratory measurements are now reported, in which the same spectroscopic apparatus is employed as is used in the atmospheric work. The absorption coefficients so found agree well with the atmospheric values.The possibility that there may be other gases in the atmosphere, in addition to ozone, which absorb in the ultra‐violet region is examined. Only sulphur dioxide might possibly give trouble but the amount present is too small to cause appreciable errors in the ozone measurements.
Zonal winds over the equator
Authors: Tucker G. B. 
Published: February 2007

AbstractThe dynamics of mean zonal flow over the Equator are described using a momentum budget. First the budget is drawn up for the troposphere, and the estimates of the mechanisms involved are shown to be consistent with the observed zonal wind/height profile. the technique is then applied to the stratosphere up to 30 km where the approximately 26‐month oscillation in zonal winds is observed. the necessity for a similar oscillation in the momentum convergence due to large‐scale horizontal eddies is deduced, and this oscillation is verified from wind observations. the vertical velocity/height profile associated with the zonal wind oscillation is derived and shown to be constant in time. the downward motion above 20 km and upward motion below is shown to be consistent with observed ozone and water vapour observations. Finally, types of synoptic systems are suggested which could be associated with the observed pattern of zonal flow and momentum convergence.
Lee wave characteristics derived from a three‐layer model
Authors: Pearce R. P. , White P. W. 
Published: February 2007

AbstractIt is well‐known that lee waves are usually associated with the presence of an inversion layer. A mathematical model in which the atmosphere is divided into three layers, the middle one being of high stability and the other two of much lower stability, enables criteria for the occurrence of lee waves to be calculated, the only parameters entering being Scorer's ‘l2’ for the middle and adjacent layers and the thickness of the middle layer expressed as a multiple of its height above the ground. Data from four cases in which lee waves were observed are compared with the characteristics of the model and reasonable quantitative agreement of wavelengths obtained.The increase in wavelength and frequent disappearance of lee waves associated with convective heating of the lower layers can be deduced from the theoretical behaviour of the model as the parameters are changed to simulate the heating process.