bluuebunny/crossref_metadata_2025 huggingface dataset:
The decay of the ice‐nucleating properties of silver iodide released from an aircraft
Authors: Smith E. J. , Heffernan K. J. , Thompson W. J.
Published: February 2007

Silver‐iodide smoke was released from an aircraft, together with a tracer of zinc sulphide, and both aerosols were detected in another aircraft. About 2 × 1014 freezing nuclei were emitted per gram of silver iodide burnt. The number of effective nuclei decreased on exposure to the air in the daytime by a factor of 1,000 in two hours. At night there was no detectable decay.
An essay on low‐latitude wind analysis
Authors: Scott J. R.
Published: February 2007

A method of wind analysis widely used in low latitudes is shown to be basically unsound, using the results of another method of analysis. It is shown that analogy may usefully be drawn between middle‐latitude and equatorial airflow. A suggestion for the use of pressure data near the equator and brief comments on well‐known types of wind analysis are made. The emphasis is on equatorial conditions.
Dust concentrations in the Harmattan
Authors: McKeown H. D. J.
Published: February 2007

A method of counting the very fine dust particles of the Harmattan and of determining their approximate size range is described, and some of the counts obtained at Ibadan, Nigeria, during the 1955–56 season are presented. It is suggested that the large dust concentrations may have a blanketing effect on terrestrial radiation.
The role of water particles in the atmospheric transmission of infra‐red radiation
Authors: Deirmendjian D.
Published: February 2007

The attenuation of infra‐red radiation by scattering on atmospheric haze particles, in the form of water droplets, is discussed in some detail. The spectrum is divided into two regions, the near infra‐red to λ 2·25 μ, where the refractive index of water may be assumed constant and real, and the region 2·25 to 12μ, where the index is complex and varies with the wavelength. This paper is concerned with the first region. It is shown that certain haze models, involving a continuous drop‐size distribution and previously used in explaining the attenuation of visible wavelengths and the aureole around the sun, adequately explain the window transmission measured by Gebbie and co‐authors (1951) along a horizontal path. The observed optical thickness of the whole atmosphere with respect to near infra‐red sunlight is also explained by means of these models.

The infra‐red attenuation spectrum appears as a logical extension of the visible one and represents the continuous background upon which gas line and wing absorptions must be superposed. The magnitude of the latter can thus be assessed with more confidence.
A theory of fronts in relation to surface stress
Authors: Ball F. K.
Published: February 2007

Surface‐stress terms are introduced into the equations governing the motion of the cold air ahead of a warm front or behind a cold front. Solutions for the steady state indicate that a katafront inversion tends to become horizontal at increasing distances from the front whereas an anafront inversion may continue to slope upwards indefinitely. The depth of cold air will, when the upper flow is curved cyclonically, actually decrease with increasing distance from a cold katafront. It is also shown that the existence of a sharp surface warm front depends on the sudden breakdown of a trailing layer of cold air. The thickness of this layer increases with decrease in latitude and as a result, sharp warm fronts are unlikely to occur at low latitudes. The conclusions concerning cold fronts are in broad agreement with Sansom's (1951) observations.
Measurements of space charge in the lower atmosphere using double field mills
Authors: Smiddy M. , Chalmers J. Alan
Published: February 2007

Two double field mills (Smiddy and Chalmers 1958) have been used to study space charge in the lowest 5 m of the atmosphere.

Results in fair weather show small values, often negative, which can be explained in terms of radioactivity of the ground. Comparison with results from filtration apparatus suggest that the latter may be in error when small ions are present in large numbers.

Results in light or moderate rain show small space charges, but in heavy rain, negative space charges of the order of – 1,000 μμc m−3 are found, probably formed by splashing. In snowfall, there are charges of both signs of about ± 500 μμc m−3.
The performance of a Gunn‐Bellani radiation integrator
Authors: Monteith J. L. , Szeicz G.
Published: February 2007

An alcohol‐filled Gunn‐Bellani radiation integrator, exposed at Rothamsted from June to December 1958, gave weekly distillation totals that were a linear function of short‐wave radiation on a horizontal surface above a limit of 500 cal cm−2 week−1. Laboratory experiments with both alcohol‐ and water‐filled models reveal a threshold radiation intensity which can be estimated from the properties of the distilling fluid and the partial pressure of air within the instruments. Distillation is negligible below the threshold, but above, it is proportional to the excess radiation. Because the relation between absorbed heat and radiation incident on a horizontal surface depends on solar altitude and on the proportions of direct and diffuse radiation, it is difficult to predict field response from laboratory data.
Some long‐term means from The Phenological Reports (1891–1948) of the Royal Meteorological Society
Authors: Jeffree E. P.
Published: February 2007

The Phenological Reports 1891–1948 of the Royal Meteorological Society are discussed; interpolated values in floral records have been re‐calculated, and 58‐yr district and British Isles weighted means, and annual differences from these, have been calculated for 11 flowering events. 20‐yr means and differences have been similarly calculated for a further 14 events, and the former approximately corrected to the 58‐yr means. For 11 main flowers in The Phenological Reports, the mean difference in flowering dates between south and north Britain was 21 days later for a distance of some 400 mi farther north. Extremes of earliness and lateness have been tabulated for the British Isles weighted means for these 11 flowers over the years 1891‐1948. Extreme earliness averaged 17‐7 days and extreme lateness 17‐1 days, but while extremes of earliness were fairly constant throughout the year or possibly became a little greater for summer than for spring flowers, extremes of lateness were much greater for spring than for late summer flowers. These differences are directionally in keeping with the finding of Hawke (1941) that in the winter months abnormally low temperatures are much more extreme than abnormally high values, while in summer the abnormally high values are more extreme than the exceptionally low. The standard deviations for the annual values of the British Isles weighted means are also given, and averaged 7‐0 days for the 11 main flowers.
Determination of the straight line of best fit to observational data of two related variates when both sets of values are subject to error
Authors: Morgan W. A.
Published: February 2007

The general equation to a straight line of best fit to observational data of two related variates x and y is obtained by minimizing the general expression \documentclass{article}\pagestyle{empty}\begin{document}$ \sum\limits_{i = 1}^n {(y_i - ax_i - b)^2 } $\end{document} ϕ(a) involving the departures of both variates from the time. It is shown that the only expression for ϕ (a) which produces consistent results with change of unit is ϕ (a) = constant. ak, where k depends on the relative errors (ex, ey) in measurements of the two variates.

The line of best fit is shown to be

where c is obtained from the equation (k + 2) c2 – 2 (k + 1) rc + k = 0, in which r is the coefficient of correlation between x and y, and k is a given function of ex and ey. The usual regression lines and line with a slope equal to the geometric mean of the slopes of the two regression lines, arise as special cases of the general equation. Examples are given to show general application.
A problem in baroclinic stability
Authors: Green J. S. A.
Published: February 2007

Linearized equations are used to formulate the theoretical problem of the stability of large‐scale zonal flow with vertical shear. The problem is solved in some generality and illustrates the connexion between the solutions already obtained by Rossby, Charney and Eady.
A direct measurement of the humidity in the stratosphere using a cooled‐vapour trap
Authors: Barclay F. R. , Elliott M. J. W. , Goldsmith P. , Jelley J. V.
Published: February 2007

A vapour trap designed for sampling the water vapour and carbon dioxide of the stratosphere is described. The results of one flight at about 27 km over south‐east England are given and discussed.
Control of inversion height by surface heating
Authors: Ball F. K.
Published: February 2007

Viscous dissipation is inadequate to account for the destruction of all the thermal turbulence generated by upward transfer of heat in a deep convection layer. It is suggested that the surplus turbulent kinetic energy is destroyed by buoyancy forces in a region of downward transfer of heat in the upper part of the convection layer. This process is associated with mass transfer downwards through the convection (or subsidence) inversion and also with an upward movement of the inversion, though the latter may be overcome by sufficiently strong subsidence. A simple theory of the process is developed and the results deduced thereby agree well with observations of the diurnal variation of inversion height in Central Australia.
Fog‐droplet sampling using a modified impactor technique
Authors: May K. R.
Published: February 2007

Possible errors in sampling fog droplets with the cascade impactor are discussed and data are presented which were obtained from 25 fogs by the use of a specially modified impactor in a small portable wind‐tunnel. A very wide range of drop diameter (< 1 to > 100 μ) was found, with great numbers of very small drops and great variability in size‐distribution. Agreement between the visual range as calculated from the drop measurements and the actual visual range was usually closer than a factor of two, though in some cases there was no such agreement.
The penetration of interfaces by cylindrical thermals
Authors: Richards J. M.
Published: February 2007

A theory is presented which connects the proportion of a cylindrical thermal which indefinitely penetrates any specified interfacial discontinuity of density with the distribution of density excess or deficit within similar thermals moving through unstratified surroundings. The relation between the proportion of the thermal which so penetrates and the strength of the inversion has been determined experimentally; the results are expressed by the empirical formula Y = (0·93 S + 1) exp (‐ 0·93 S), where Y is the fraction of the mass of the substance released which penetrates, and S = Δp1 A1/M, where Δp1 is the change of density across the interface in the direction of motion of the thermal, A1 is the measured cross‐sectional area of the thermal when its widest part is at the initial level of the interface, and M is the initial mass excess of the thermal per unit length. The theory then predicts that, in cylindrical thermals moving through unstratified surroundings, T/A = exp (‐ Δp A/M), where A is the average cross‐sectional area of the thermal, M is its mass excess or deficit per unit length, and T is the total average cross‐sectional area of all regions within which the density excess or deficit, respectively, is greater than or equal to Δp.

Mean cross‐sectional distributions of a passive pollutant have been determined experimentally in three thermals moving through unstratified surroundings. The results were roughly consistent with the expression α/A = exp (‐ $C/$C), where A has the previous meaning, $C is the average concentration of the pollutant over the whole thermal, and α is the mean total cross‐sectional area of all regions within which the concentration of pollutant, averaged over the length of the thermal, is everywhere greater than or equal to ΔC.

These and other observations seem to show that cylindrical thermals are usually appreciably non‐uniform along their lengths.
The formation of ammonium sulphate in water droplets exposed to gaseous sulphur dioxide and ammonia
Authors: Van Den Heuvel A. P. , Mason B. J.
Published: February 2007

The rate of formation of ammonium sulphate in water drops exposed to air containing known concentrations of gaseous sulphur dioxide and ammonia has been measured. The mass of sulphate formed is proportional to the product of the surface area of the drops and the time of exposure. Extrapolation of the laboratory results to the atmosphere suggests that the large condensation nuclei 0·2 μ < r < 1 μ of ammonium sulphate, found by Junge to be abundant in industrially polluted air, are formed by the absorption of SO2 and NH3 in cloud and fog droplets.
The absorption of solar infra‐red radiation by the lower stratosphere
Authors: Houghton J. T.
Published: February 2007

Aircraft observations of the absorption of solar infra‐red radiation by the atmosphere are compared with values of integrated absorption predicted from laboratory measurements on water vapour and carbon dioxide. Aircraft observations of bands due to O2, CO, CH4 and N2O are also considered. A scheme is derived for computing, for different latitudes and seasons, the heating‐rate due to the absorption of solar infra‐red radiation at altitudes between 10 km and 40 km. The results of such computations are presented.
A note on the frictional boundary condition at the earth's surface in relation to a model of the general atmospheric circulation
Authors: Oakes M. B.
Published: February 2007

In a paper by Davies and Oakes (1962) concerning the problem of formulating a model of the general atmospheric circulation, the boundary condition used at the surface of the earth involved the assumption that the surface meridional, zonal, and vertical velocities are zero. In this note the effect on the model is evaluated by using as boundary condition at the earth's surface the more realistic assumption that the Reynolds stress is proportional to the first power of the surface wind speed.
The motion and structure of stellar shadow‐band patterns
Authors: Protheroe W. M.
Published: February 2007

The structure of stellar shadow bands has been measured on eighteen nights using an optical Fourier analyser technique. The mean size of the pattern elements was found to be 15.6 cm. The measured pattern speed and direction of motion agreed reasonably well with the upper‐air winds in the neighbourhood of 30,000 ft. The lifetime of the shadow‐pattern elements was found to be of the order of tens of milliseconds.
Factors affecting the heat transfer from hailstones
Authors: Macklin W. C.
Published: February 2007

The rate of heat transfer by forced convection from rotating and oscillating spheroids of ice has been investigated and it is shown that these factors are unlikely to influence the rate of heat transfer from hailstones. Turbulence, however, does affect the rate of heat transfer and it is suggested that some of the transitions from clear to opaque ice observed in hailstones could be caused by the influence of the turbulent wake of one hailstone on another.

The effect of prolonged melting on shape is also discussed.
An index of clear air turbulence
Authors: Colson D. , Panofsky H. A.
Published: February 2007

An index is derived for the intensity of turbulence in a sloping baroclinic layer. Preliminary estimates of this index from ordinary meteorological information suggest that the index is proportional to turbulent energy and that it discriminates better between regions of varying intensity than vertical wind shear or Richardson number. An exact test, however, would require more detailed synoptic information than is usually available.
Radiation balance of natural and agricultural vegetation
Authors: Stanhill G. , Hofstede G. J. , Kalma J. D.
Published: February 2007

The three constants of a radiation‐balance equation ‐ albedo, heating coefficient and long‐wave radiation balance at zero insolation ‐ have been derived from linear regression equations relating measurements of incident and reflected short‐wave radiation to measurements of radiation balance (all wave‐lengths) made over nine different associations of natural vegetation and two agricultural surfaces. Albedo was found to be the most important discriminant in the relationship, varying from 0.12 for a pine forest to 0.37 for vegetation in a desert wadi. The diurnal and seasonal variations were small and of limited significance. The heating coefficient varied considerably, both with date of measurement and with vegetation, but no consistent differences could be seen. The values found were very low, even negative on a number of occasions. These were associated with a mid‐day decrease in the long‐wave balance attributed to a marked increase in the long‐wave flux from the sky. The long‐wave balance at zero insolation also varied considerably with date of measurement and type of surface but showed only small differences in long‐term mean values.

Daily totals of net radiation balance expressed as percentages of total incoming short‐wave radiation varied from a maximum of 58 per cent for the open water surface of a fish pond to a minimum of 25 per cent for a desert association. The ratio for most vegetation was close to 50 per cent.
Further data concerning the distribution of water vapour in the stratosphere
Authors: Murcray D. G. , Murcray F. H. , Williams W. J.
Published: February 2007

The variation of the infra‐red solar spectrum with altitude was observed during a balloon flight made on 24 March 1964, from Alamogordo, New Mexico. A water vapour mixing ratio profile determined on the basis of the variation with altitude of the infra‐red solar spectrum in the vicinity of 3,854 cm−1 during this flight is presented. This profile is in agreement with the view that the mixing ratio in the vicinity of the tropopause is about 2.10−6 g g−1; however, it also indicates that the mixing ratio increases again above 65,000 ft.
The budget of turbulent energy near the ground
Authors: Hess G. Dale , Panofsky H. A.
Published: February 2007

On the basis of wind records on two days at the Brookhaven tower at Upton, New York, it is tentatively concluded that, in equilibrium, mechanical energy production and energy dissipation are not significantly different from each other, even if the stratification is quite unstable. Change from rough to smoother terrain, however, produces a state of non‐equilibrium in which dissipation may greatly exceed production.
The effect of contamination on spectroscopic determinations of stratospheric water vapour
Authors: Houghton J. T.
Published: February 2007

The effect is considered of the presence of water vapour in the optical path of a spectrometer used to measure absorption by atmospheric water vapour. If such possible contamination is ignored, the water vapour mixing‐ratio profiles deduced from the measurements will show increasing mixing‐ratio with altitude in the stratosphere.
An approximate treatment of the effect of thermal stability on turbulent diffusion
Authors: Gee J. H.
Published: February 2007

Assuming a wind profile of form u oc zm where m is a function of the stability parameter L, the effect of stability on turbulent diffusion is investigated. Swinbank's exponential wind profile yields the relation m = 0.1340 + 0.244 L−1 + 0.22 L−2 and a drag coefficient implied by \documentclass{article}\pagestyle{empty}\begin{document}$ \[ \frac{{u_1 }} {{u_* }} = \frac{1} {k}In\left[ {\frac{L} {{z_0 }}\left( {\exp \left\{ {{2 \mathord{\left/ {\vphantom {2 L}} \right. \kern-\nulldelimiterspace} L}} \right\} - 1} \right)} \right] \] $\end{document}.

On this basis, curves showing the dependence of point‐concentrations on stability are drawn for eddy diffusion and evaporation problems. These indicate, among other things, the existence of a lower region where concentration increases with stability and an upper region where concentration decreases with stability; they also show that the total rate of evaporation from a liquid surface decreases by about five per cent as L−1 increases from −0.2 m−1 to + 0.2 m−1.
A preliminary map of summer albedo over England and Wales
Authors: Barry R. G. , Chambers Ruth E.
Published: February 2007

Albedo data are presented from ground and airborne measurements over different types of cover in Southern England. Summer values show a range of at least 10 per cent (15 per cent for heath, 16 to 18 for woodland and built‐up areas and 24 to 25 per cent for green cereals and grass). These and published albedos are used to prepare a map of summer albedo over the country based on the vegetation maps in The Atlas of Britain.
A note on the effect of directional wind shear on medium‐scale atmospheric diffusion
Authors: Gee J. H.
Published: February 2007

Diffusion of matter from an instantaneous point source in a directional wind shear is treated theoretically using the eddy diffusion equation, and the results are compared with medium‐scale diffusion experiments by Pasquill (1962) and with deductions based on a statistical theory by Högstrom (1964). The effect of ‘shearing advection’ on the theoretical solution is also considered and (contrary to previous results by Gee and Davies (1963, 1964) concerning diffusion near the surface) this is shown to be small, if the theory is based on the assumptions that the vertical eddy diffusivity and the vertical mixing length are constants.
Laplace's tidal equations – an application of solutions for negative depth
Authors: Corby G. A.
Published: February 2007

It is shown that solutions of Laplace's tidal equations in the presence of a non‐zero zonal flow may be obtained from the usual solutions for perturbations about a state of rest relative to the Earth, provided one uses an appropriate modification of the equivalent depth. Typically the modification leads one to the solutions which for zero zonal flow would be applicable to negative depths.
Division of radiative streams into internal transfer and cooling to space
Authors: Green J. S. A.
Published: February 2007

The equation for radiative flux divergence in a stratified atmosphere is derived from first principles. Cooling to space, and internal transfer, are seen as distinct physical processes which merit independent treatment.
The surface configuration and internal structure of artificial hailstones
Authors: Bailey I. H. , Macklin W. C.
Published: February 2007

An experimental study has been made of the external and internal structure of artificial hailstones grown freely supported in a vertical wind tunnel. In addition the nature of ice deposits formed on fixed stationary objects and objects rotating about a horizontal axis has been investigated at airspeeds of 35 to 40 m s−1. Lobe‐like growth similar to that found in natural hailstones has been reproduced. The lobes are most pronounced when the accreted droplets are small and when growth takes place near the wet limit. With large droplets and when the growth is very spongy the surface irregularities are far less marked. It is inferred that the lobe‐like growth is due to a collection efficiency effect.

The drag coefficients of a number of artificial hailstones have been measured. None of the values is greater than 0·66. Some of the moderate sized stones (4 to 6 cm diameter) entered the critical flow regime where their drag coefficients were considerably reduced. This did not occur, however, for large (10 cm diameter) very irregular hailstones.
Heat transfer from artificial hailstones
Authors: Bailey I. H. , Macklin W. C.
Published: February 2007

The rate of melting of realistically rough artificial hailstones in an airstream has been measured and the dependence of the rate of heat transfer on Reynolds number determined. The rates of heat transfer show a marked divergence from the values for smooth spheres as the Reynolds number increases from 104 to 2 × 105. The results indicate that the effective critical liquid water concentrations of large hailstones (diameters greater than 6 cm) are 1·2 to 3 times those previously computed.
Microbarographic oscillations produced by nuclear explosions as recorded in Great Britain and Eire
Authors: Mackinnon R. F.
Published: February 2007

A summary is presented of previously unpublished microbarographic data associated with atmosphere thermonuclear bomb tests in the Marshall Islands and in the Soviet Union from 1954 to 1962. Some effects of winds upon atmospheric pressure waves are indicated through study of wind conditions over the paths of propagation and through comparison with reported Japanese data. It is shown that, as well as the speed of the waves, the maximum amplitudes of wave‐trains depend upon wind conditions so that estimates of the size of explosions must take into account prevailing winds. The possible usefulness of microbarograms in the study of upper atmospheric winds is indicated.
Some numerical experiments using a two‐level general circulation model
Authors: Davies D. J. , Davies D. R.
Published: February 2007

A two‐level quasi‐geostrophic model, developed to probe into certain large‐scale features of the general circulation of the atmosphere, is discussed together with two main results of particular interest. Firstly, on averaging over longitude and over a typical cycle in eddy kinetic energy, the model indicates a functional dependence of meridional flux of zonal momentum on latitude which is approximately in step with the dependence of meridional temperature gradient on latitude. Although it is known that this type of model is not accurate in describing the motion of very long waves, the result gives some interesting theoretical support for one of the basic premises of the long time period average model of the general circulation discussed by Williams and Davies (1965). Secondly, the significance is clearly demonstrated of the particular functional forms chosen for the initial distribution of perturbation stream function values, as used in the past in a great deal of general circulation work. This is achieved by working from several initial distributions and noting that the ensuing differences in large‐scale characteristics are very clearly stamped on the flow for at least the thirty days of time integration considered in this paper. From the standpoint of calculating a ‘theoretical limit of predictability of the atmosphere’ these results can therefore be interpreted to indicate that the functional form assumed for the distribution of the initial perturbations could appreciably influence a calculation of this limit, although such calculations were not carried out in this paper. Several other results concerning the influence on these large‐scale characteristics of the forms adopted to describe vertical transfer of momentum and of total heating function are also discussed, together with the effects of introducing certain alternative computing schemes.
Momentum transport by gravity waves
Authors: Bretherton F. P.
Published: February 2007

A review of theories concerning the propagation of internal gravity waves in a horizontally uniform shear flow concludes that an upward transport of horizontal momentum inevitably accompanies the generation of such waves in the atmosphere, the mean flow being affected only at precisely those levels where the waves are dissipated. If the mean wind depends on horizontal position there may be a continuous transfer of momentum from the waves to the mean flow during propagation. In the absence of intense clear air turbulence or a critical level where the intrinsic frequency vanishes, many waves propagate upwards to great heights, even if the mean wind is time dependent. Computations of the wave drag in a 19 m s−1 gradient wind over hilly terrain in north Wales show that on that occasion it amounted to 4 dyne cm−2, of which 3 dyne cm−2 probably acted on the atmosphere above 20 km.
The effects of spectral resolution on total ozone measurements
Authors: Vanier J. , Wardle D. I.
Published: February 2007

The effect of the finite width of the wavelength bands passed by spectrophotometers used to measure the total ozone overhead is discussed. For a Dobson spectrophotometer the effect is negligible. For a spectro‐photometer with wide slits, designed for use on a star, the effect is significant. For a filter instrument the effect is so large as to represent a serious obstacle to the use of the instrument, particularly if allowance is made for the effects of haze.
The spreading of accreted droplets
Authors: Macklin W. C. , Payne G. S.
Published: February 2007

Measurements of the spreading factor of accreted droplets (the ratio of the final radius to the initial radius) have been determined over a wide range of impact speeds and ice deposit temperatures for ambient temperatures of −11 and −22°C and droplet radii of 17 and 54μ. The spreading factors vary from 2 to 6 and depend primarily on the impact speed and deposit temperature.
An alternative procedure for the evaluation of a balanced wind
Authors: Woodroffe A.
Published: February 2007

A numerical procedure is described for determining, in a barotropic model, the horizontal wind (V) from the field of geopotential height, based on the approximation d2 V/dt2 = 0. The technique used to solve the resultant simultaneous equations is outlined and some of the problems which were encountered in their solution are also mentioned. The approximation permits the evaluation of the geopotential height tendency and a comparison is made between barotropic forecasts based on this condition and on conventional barotropic and baroclinic numerical integrations.
Profile relationships: The log‐linear range, and extension to strong stability
Authors: Webb E. K.
Published: February 2007

The diabatic mean profile forms in the surface layer are studied, by applying analysis methods having high resolving power to data from O'Neill, U.S.A. (heights up to 6.4 m) and from Kerang and Hay, Australia (heights mostly up to 16 m).

It is found, concordantly from the O'Neill and Australian data, that the log‐linear law is valid for z/L values between — 0.03 and + 1, which includes a small range of unstable and a surprisingly wide range of stable conditions. For all quantities studied (wind, potential temperature, and specific humidity), it is concluded that the Monin‐Obukhov coefficient α is near 4.5 in unstable and 5.2 in stable conditions, within a standard error of about 10 per cent. The ratios KH/KM and KW/KM evidently remain constant, equal to unity, over the whole of the log‐linear range (and somewhat beyond).

In stable conditions, the log‐linear law implies that Ri approaches a critical value α−1, approximately 0.2, as z/L → ∞. However, at z/L a second régime sets in, in which the profiles are only quasi‐determinate, approximating, on the average, a simple logarithmic form (gradients proportional to z−1); this régime covers the range approximately 1 < z/L < (α + 1), i.e. (α + 1)−1 < Ri < 1. A third range of extreme stability, Ri > 1, is practically unrepresented in the data examined.

The major part of the unstable range, for z/L < − 0.03, will be discussed in a later paper.
Transfer properties of the large‐scale eddies and the general circulation of the atmosphere
Authors: Green J. S. A.
Published: February 2007

The transfer of heat and momentum by motion on the scale of cyclone waves and long waves is deduced from a knowledge of their mechanics. The law of horizontal transfer of entropy is independent of notions of mixing but is similar to that for non‐isotropic diffusion. The law accurately represents the annual variation of heat‐flux in the Northern Hemisphere. Perturbation theory suggests realistic spatial variations for the transfer and provides a rational basis for calculating transfer coefficients which can then be used to find the flux of other conservative quantities. Most importantly the Equatorward flux of potential vorticity is well defined and is shown to determine the horizontal flux of momentum uv. The mean surface winds, and the mean meridional circulation (which is seen to be frictionally driven) are then determined. A model of the general circulation is defined by these properties, and this is integrated analytically for a simplified case and compared with motion observed in the Gulf Stream, the mesosphere, and dishpan experiments as well as the troposphere.
Fluctuations of horizontal wind speed near the ground in convective conditions
Authors: Coulman C. E.
Published: February 2007

Simultaneous records of temperature fluctuations and wind speed at several heights have been obtained with instruments suspended from captive balloons flying 225 m above level, uniform land.

Variations in the horizontal wind speed near the ground appear to be associated with bursts of temperature fluctuation at heights of more than about 100 m in a way which suggests that convective plumes, or ‘thermals,’ become organized within the lowest few metres of the atmosphere.
Electrification accompanying the freezing of water
Authors: Dawson R. , Hutchinson W. C. A.
Published: February 2007

75‐ml samples of de‐ionized, distilled water were frozen and electric potential differences between similar electrodes in the ice and water respectively were measured as functions of time, rate of freezing and temperature differences within the ice layer. The charge separation at the ice/water interface caused by selective rejection of ions always exceeded that due to temperature gradients within the ice at freezing rates greater than 10 μm s−1.
The variation of the electric field after lightning and the conductivity within thunderclouds
Authors: Illingworth A. J.
Published: February 2007

It has been found that the rate of growth of field following a close lightning discharge is explicable in terms of the regeneration of the dipole by a constant current and a charge loss governed by the fair weather conductivity at the height of the charge. The recovery may be influenced by local point discharge after large field‐changes, but the presence of a core of high conductivity within the cloud need not be invoked. The recovery curves from close flashes are found to be rather irregular and no really useful information concerning the currents generating the dipole of the thunderstorm can be derived from them. As the distance of the storm increases then the recoveries become much more rapid and of reproducible shape. It is suggested that after the discharge the re‐arrangement of the space charge existing because of the conductivity gradient in the atmosphere is responsible for the change of the field observed. Some numerical work gives fair agreement with the observed functional dependence of the initial rate of recovery on the size of the field change. These distant recoveries are the response of the conducting atmosphere to the field change, and can give no useful information about the thunderstorm itself.
Measurements of submillimetre wavelength radiation emitted by the stratosphere
Authors: Harries J. E. , Burroughs W. J.
Published: February 2007

Observations have been made of the submillimetre wavelength radiation emitted by the lower stratosphere, using techniques of Fourier transform spectroscopy, while flying in a Comet 2E aircraft. Using the method of phase‐modulation high quality spectra have been obtained at several altitudes over the spectral range 20 to 66 cm−1, and these have enabled identification of many emission lines due to O2 and O3, in addition to those of H2O. Also several unidentified emission lines have been observed. The meteorological applications of this spectroscopic technique are considered. In particular, a direct method of comparing the emission of ‘strong’ water‐vapour and oxygen lines enables a calculation of mixing ratio of water vapour in the stratosphere to be made, and a value of (2.1 ± 0.3) × 10−6 g/g is derived above an altitude of 12.2 km. A similar comparison for ozone has given an integrated concentration of 0.35 ± 0.10 cm atm in the vertical path above the observer. The merits of these observations in measuring stratospheric mixing ratios are discussed with respect to alternative techniques, in particular with reference to balloon‐borne studies.
The albedo of a pine forest
Authors: Stewart J. B.
Published: February 2007

The albedo of a pine forest was measured for a total of 243 hours during the summer of 1970 by pairs of Kipp solarimeters whose output was recorded by a computer controlled data acquisition system. It was found that the mean albedo was 9.1 per cent. On cloudless days there was a pronounced dependence of albedo on solar zenith angle; however, on cloudy days there was little variation. The effect on the albedo of the wetness of the canopy was less than one per cent except at large solar zenith angles. The mean albedos for June and December were calculated and found to be 8.9 and 11.7 per cent respectively.
The surface drag contribution to the depth of Atlantic, and European, depressions
Authors: Dodds I.
Published: February 2007

Estimates are made of the forced ωF‐components arising from surface frictional inflow within the circulation of an ‘average’ Atlantic and an ‘average’ European depression. When allowance is made for the high curvature flow by the inclusion of a centripetal acceleration term in the equation of motion, it is found that the ωF‐contribution at the top of the boundary layer, is much the same in each case. The quasi‐geostrophic ω‐equation is solved to obtain the three‐dimensional ωF‐field accompanying the average depression. This gives a value of ∂ωF/∂p at the centre of the depression, and using this in the geostrophic vorticity equation it is found that surface friction makes a positive contribution of about 4 mb day−1 to the central pressure tendency in each case.
The stability of charged drops in uniform electric fields
Authors: Brazier‐Smith P. R.
Published: February 2007

Stability criteria of charged drops levitated by uniform electric fields are determined by assuming that the drops possess spheroidal equilibrium shapes and that the equations of equilibrium are satisfied at the two poles and the equator. The stability criteria were also determined by the more precise method prescribed by Brazier‐Smith (1971). Comparison of the results of the two methods indicates that the spheroidal assumption, which was applied with considerable success to study the stability of uncharged drops, cannot be applied to cases in which the drops are charged.
The vertical propagation of angular momentum in the west wind belts
Authors: Clarke R. H.
Published: February 2007

Boundary layer data from the Wangara expedition show that, at a point in the mean winter west wind belt (but near its equatorward limit), eddies on the synoptic scale (periods greater than a day) transferred westerly momentum upward. Except in the lowest 500 m, this upward tranfer predominated over downward fluxes due to micro‐scale (periods less than 2 hours) and meso‐scale (2 ‐ 24 hours) eddies, the latter transfers being very small. The effect of ageostrophic motions, due to accelerations, on this transfer was negligibly small.

A characteristic circulation, relative to synoptic systems, in a vertical zonal plane, performing the vertical transfer of westerly momentum, has been deduced.

The eddy flux of angular momentum, in the middle latitude boundary layer between 500 and 1,700 m appears to be directed up the angular momentum gradient, both horizontally and vertically, and, at all levels, down the horizontal gradient of angular velocity.

An argument is presented to show that the intensity of circulation in the Ferrel cell may be greater than is usually estimated, the maximum absolute value of the stream function (except for the Northern Hemisphere in summer), being normally at least about 30 × 1012 g s−1.
Aircraft measurements of dissipation of turbulent kinetic energy
Authors: Taylor R. J.
Published: February 2007

Fifty values of the rate of dissipation of turbulent kinetic energy, ε, deduced from spectra of vertical air velocity component made from an aircraft are presented. While generally in the range of values found by other authors the distribution of ε with height shows a good deal of scatter. This can in large measure be resolved by grouping the observations according to site roughness, season and wind speed, thus allowing for the varying contributions to ε of the wind‐shear and buoyancy‐force terms.

The characteristic decay time of the turbulence (defined as the variance of vertical velocity divided by ε) increases consistently as the square root of height.
Diurnal variation of temperature and wind in the equatorial stratosphere
Authors: Hamilton R. A. , Shearman R. J.
Published: February 2007

Rocket soundings were made at Gan (0°41′S, 73°09′E) after sunset and before sunrise to determine the change of temperature and wind during the night. The soundings showed that the change of temperature varied with height, being positive around 54 km, negative around 44 km, and mainly positive between 30 and 40 km, in general agreement with Lindzen's tidal theory. The zonal wind also showed a tidal variation. An analysis of day and night rocket soundings at Ascension Island (07°59′S, 14°25′W) indicates that the winds show a tidal variation, but the heights of the isobaric surface in the stratosphere are always a maximum around noon, suggesting an error in the temperature measurements due to solar radiation.
Turbulence measurements over the sea by a tethered‐balloon technique
Authors: Thompson N.
Published: February 2007

Turbulent fluctuations of wind, temperature and humidity at heights up to a few hundred metres have been measured over the open sea by instruments supported by a tethered balloon. Wave‐induced motion of the ship from which the balloon was flown produced unwanted contributions to the measured turbulence, but in light or moderate winds it has been possible to make allowances for these effects and to obtain useful estimates for vertical fluxes of heat and moisture: the calculated momentum fluxes in contrast appear less reliable and to obtain satisfactory values will require stabilization of the tethering point of the balloon cable. Some observations made in generally unstable conditions near OWS ‘J’ yield a value of (1.8 ± 0.7) × 10−3 for CE in the bulk aerodynamic formulation for evaporation (E = ρCE (q0 − q10)(U10 − U0)) and suggest that compared to the vertical moisture flux the heat flux may often have an insignificant rǒle in determining the buoyancy flux and hence the turbulence structure in the bulk of the boundary layer.
Airborne dust collections down the Atlantic
Authors: Parkin D. W. , Phillips D. R. , Sullivan R. A. L. , Johnson L. R.
Published: February 2007

The airborne dust concentration in the Atlantic varies from 102μg/m3 of air near the Sahara coast to as little as 10−5μg/m3 over the Antarctic ‐ for particles > 0.5μm diameter.

Dust collector meshes have been exposed on the bows of a ship (February‐March 1971) during the outward and return voyage between the Canary Isles and the River Plate. There is an order of magnitude change in concentration on crossing the Equator around 30°W. The dusts south of the Equator are borne on the south‐east trades and probably come from the Namib desert; their particle sizes are smaller than those coming from the nearer Sahara desert. The colour of the dusts on either side of the Equator are grey due to an admixture of black humus; off the Sahara coast they are brown and clean‐looking. The quartz to clay ratio increases with nearness to land but the kaolinite to illite ratio is symmetrical about the Equator, the savannah lands being rich in kaolin. Daily satellite photographs clearly show veils of dust crossing the coast at Dakar and some attempt has been made to relate these to the ship‐borne collections.
Inexpensive instruments for the measurement of solar radiation
Authors: Smith G. W.
Published: February 2007

Four inexpensive solarimeters were compared with a standard. Mean errors (on a daily basis) were 5 per cent for the Gunn‐Bellani, 9 per cent for the Campbell‐Stokes, 10 per cent for the bimetallic actinograph and 12 per cent for the Sol‐a‐Meter. The corresponding weekly errors were 2–5 per cent, 3 per cent, 3.5 per cent and 4.5 per cent. A fifth instrument was not included because daily totals were difficult to obtain.
A numerical experiment using a general circulation model of the atmosphere
Authors: Gilchrist A. , Corby G. A. , Newson R. L.
Published: February 2007

The general circulation model whose formulation is described in Corby et al. (1972) was integrated for 60 days from real data with January radiation and sea surface temperatures. The deficiencies of the model as a representation of the atmosphere were revealed by the extent and rate of the systematic changes as an equilibrium state was approached. For the first ten days, the model lost eddy kinetic energy, then gradually recovered and from about day 30 its tropospheric simulations both synoptically and in its time‐mean cross‐sections at various longitudes, had many realistic features; it failed, however, to maintain a substantial Siberian winter anticyclone. A major weakness, resulting from the use of a single level to represent the 0–200 mb layer, was the progressive deterioration of the model stratosphere.
Stereo photogrammetry of cumulonimbus clouds
Authors: Warner C. , Renick J. H. , Balshaw M. W. , Douglas R. H.
Published: February 2007

A technique is described for stereo photogrammetry of clouds. Movie cameras are set up on a ground baseline 5·6 km long. Time‐lapse films are made with a frame interval of 3 s. The analysis involves the super‐imposition of stereo pair images of the cloud, with advantages over methods previously used.

Measurements are presented of an Alberta hailstorm, and estimates are made of horizontal divergence near the cloud tops, and mass flux. Measurements and calculations imply that the ring vortex model of the circulation in small cumulus tops is applicable to some large hail‐bearing storms, and that little or no net mass transfer occurs through the caps of rising cloud towers.
Equatorial Kelvin waves at 100 millibars
Authors: Parker D. E.
Published: February 2007

A marked oscillation with a periodicity slightly greater than a month occurred in the zonal wind at 100 mb over Gan (00°41′S, 73°09′E) through the months January to May 1966. Corresponding oscillations took place during this period over other equatorial stations round the globe, but on the whole the oscillations became weaker with increasing latitude. The meridional wind was not directly involved in the oscillations, which were manifestations of a wave which generally progressed eastward relative both to the earth and to the mean flow with, however, a somewhat irregular rate of progression. The wave had zonal global wave number 1. Although it also advanced southward over the eastern hemisphere, it was not far from being symmetrical (as opposed to antisymmetrical) about the Equator. It was largely confined to the region between 150 mb and 70 mb, but it generally propagated downwards, Over the eastern hemisphere the 100 mb temperature tended to lead the 100 mb zonal wind by about 1/4 cycle. At least over Gan the 100 mb height and the 100 mb zonal wind tended to be in phase. The effect as a whole was sufficiently like an equatorial Kelvin wave to be considered as such. especially over the eastern hemisphere.

The wave was linked very indirectly to concurrent events at 100 mb at 40°N. Less marked equatorial Kelvin waves occurred at 100 mb in 1960, 1967 and 1969. The incidence of equatorial Kelvin waves at 100 mb did not appear to be closely related to the phase at 50 mb of the tropical quasi‐biennial zonal wind oscillation.