摘要:

AbstractA calculation has been made of the meridional circulation sufficient to transport heat between the radiational sources and sinks in the stratosphere (15‐55 km) and mesosphere (55‐80 km). Assuming that the principal heat sources are in the region of the equatorial tropopause and in the mesosphere over the summer pole, with the corresponding heat sinks near the polar tropopause and over the winter pole in the mesosphere, the main circulation patterns are found. Below 30 km there is rising air over the equator with outflow towards both poles and descent towards the tropopause in high latitudes in both hemispheres. At higher levels there is ascent over the summer pole and descent over the winter pole with a well defined flow towards the winter pole above 50 km and a more indeterminate flow pattern between 30 and 50 km. The order of magnitude of the speed of these circulations is m sec−1horizontally and cm sec−1vertically.The calculations were made for the solstices, equinoxes and mid‐times between them and several particle trajectories were determined. The results are in agreement with many of the observed physical features of the stratosphere and mesosphere, particularly the distribution of tracer

ISSN:0035-9009    

DOI:10.1002/qj.49708737202

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractA primitive equation model is formulated and integrated numerically to study the sea breeze. The formulation is an extension of an atmospheric boundary‐layer model previously developed for a homogeneous terrain. External gravity‐wave type solutions are suppressed by a modelling assumption involving the equation of continuity. The results of an integration showing the evolution of the sea breeze under conditions of no large‐scale synoptic motion are pres

ISSN:0035-9009    

DOI:10.1002/qj.49708737203

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe frequency of various types of ‘present‐weather’ observations are analysed and a method is derived using these to obtain estimates of mean monthly precipitation. The method is applied to observations from ocean weather ships in the North Atlantic Ocean to obtain the mean monthly, seasonal and annual precipitation over the ocean during the five‐year period 1953 to 1957. The results are then compared with previous es

ISSN:0035-9009    

DOI:10.1002/qj.49708737204

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractIncoming short‐wave radiationS, reflected short‐wave radiation αSand net radiationRwere measured over bare soil and crops from 1957 to 1959, and net long‐wave radiation (L) was deduced from\documentclass{article}\pagestyle{empty}\begin{document}$$R = (1 - \alpha)S + L$$\end{document}For grass, α increased from 0·23 at solar elevation 60° to 0·28 at 20° with daily mean 0·26. For bare soil, the corresponding increase was from 0·16 to 0·19 with mean 0·17. In mid‐June,Lfor bare soil decreased from – 0·1 cal cm−2min−1during the night to – 0·4 cal cm−2min−1in the early afternoon. For long grass, in August, the corresponding change was from – 0·05 to – 0·22 cal cm−2min−1. Under clear skies the incoming long‐wave component varied much less than the outgoing component, and net fluxLwas closely related to surface temperature.With a heating coefficient β = –dL/dR, the observed linear dependence ofRonSin the absence of cloud may be expressed as\documentclass{article}\pagestyle{empty}\begin{document}$$R = (1 - \alpha)S + L$$\end{document}Where, formally,R=L0whenS= 0. For grass, sugar beet and potatoes, β lay between 0·15 and 0·22 with a variation which may depend on wind speed rather than on crop. The value for dry bare soil was higher (0·41) because there was greater surface heating.Measurements under clear skies and over grass at Cambridge and Kew agree well with Rothamsted values (β = 0·22,L0= – 5·9 cal cm−2hr−1). Over Nebraska prairie, β = 0·25,L0= – 4·5 cal cm−2hr−1from

ISSN:0035-9009    

DOI:10.1002/qj.49708737205

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractFrom radiation measurements at Kew Observatory (tabulated by Lönnqvist), the effective emissivity of the atmosphere ε, defined as the ratio of incoming long‐wave radiation to black‐body radiation at screen temperature, can be related to optical pathm(cm) by\documentclass{article}\pagestyle{empty}\begin{document}$$ \varepsilon = 0 \cdot 70 + 0 \cdot 22\log m $$\end{document}With standard deviation ± 0·018. The relation betweenmand surface vapour pressuree(mb) found from Belasco's (1952) air mass analysis is\documentclass{article}\pagestyle{empty}\begin{document}$$ \log m = 0 \cdot 29\sqrt {e - 0 \cdot 80} $$\end{document}giving\documentclass{article}\pagestyle{empty}\begin{document}$$\varepsilon = 0 \cdot 53 + 0 \cdot 065\sqrt e$$\end{document}almost the same as Brunt's equation from Benson data.Net long‐wave radiationLover short grass can be calculated from\documentclass{article}\pagestyle{empty}\begin{document}$$L = (1 - c)(\varepsilon - 1)\sigma T_{A^4 } + _c L_1 - L_2$$\end{document}wherecis fractional cloudiness; σTAis black‐body radiation at screen temperature; ΔL1is a correction for the difference betweenTAand cloud‐base temperature; and ΔL2for the difference betweenTAand surface radiative temperature. From Roach's Kew data, ΔL1= – 18 cal cm−2day−1and ΔL2varies with season from – 12 cal cm−2day−1(December) to + 20 cal cm−2day−1(June). Throughout the British Isles, annual meanLwithc= 0 is close to – 200 cal cm−2day−1, and for real values ofc\documentclass{article}\pagestyle{empty}\begin{document}$$ L = 178c - 200{\rm cal cm}^{{\rm - 2}} {\rm day}^{{\rm - 1}} $$\end{document}Estimated annual net (total) radiation is 29 k cal cm−2wi

ISSN:0035-9009    

DOI:10.1002/qj.49708737206

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractA series of records, totalling over 120 hr showing the vertical fluctuations of high‐response wind‐vanes positioned on a captive balloon cable, are analysed to give statistical information on turbulence at heights between 500 and 5,000 ft, for an eddy frequency range 0·003‐12 cycles min−1. The use of specially designed filter and smoothing circuits facilitates the determination of the angular standard deviation of the inclination of the vane, as a function of run of wind, and of spectra, length‐scales and other parameters of turbulence. 18 spectra are given which show well‐defined peaks. Except in very stable conditions, the high wave‐number forms of the spectra are generally consistent with the existence of an inertial sub‐range. Estimates of the length‐scale, again excluding very stable conditions, do not apparently vary with height and average about 300 m. Intensity is found to depend on stability and to decrease in a very marked way with increasing wind speed, a result peculiar to these heights. This variation, applicable to specified meteorological conditions, is shown to have value in the determination of the spread of both continuous‐source plumes and clusters of particles according

ISSN:0035-9009    

DOI:10.1002/qj.49708737207

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractResults of a study of about 70 spectra of the horizontal components of gustiness in strong winds are described. From these and other published data the following expression for the spectrum of gustiness for strong winds in the lower layers is suggested:Cross‐spectra and cross‐correlations of velocity between pairs of stations on a mast are given. From this it appears that the cross‐spectra can be expressed as a simple function of the ratio of the vertical separation to the wavelength, no dependence on height being detec

ISSN:0035-9009    

DOI:10.1002/qj.49708737208

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractNumerical computations are made to show how the vertical velocity, temperature, humidity‐mixing ratio and liquid‐water content of a cloudy parcel will vary with height and time as it ascends from the condensation level, rises through, and mixes with, the surrounding environment whose temperature and humidity distributions are specified. The rate at which the parcel is diluted by mixing is formulated in two different ways which lead to essentially the same conclusions. This treatment does not attempt a detailed description of the mixing processes but arrives at rather critical values for a single parameter used to represent the rate of mixing. If this is sufficiently large to prevent the vertical motion undergoing large oscillations (such as are experienced by a closed parcel), the first‐formed cloud is small ‐ usually only a few hundred metres deep over land and perhaps less than 100 m deep over the oceans. This implies that large clouds must evolve by successive thermals rising through air which has been warmed and moistened by their predecessors. Computations are made to demonstrate this stage‐by‐stage growth. The formation and growth of the first visible cloud appears to depend rather critically upon the excess temperature and velocity with which the thermal reaches the condensation level. These conclusions, and also the computed vertical profiles of temperature, updraught speed and liquid‐water in these small clouds, appear to be consistent with

ISSN:0035-9009    

DOI:10.1002/qj.49708737209

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThunderstorms containing hail have been found to have extremely large radar reflectivities. Experimental work by Atlas, Harper, Ludlam and Macklin (1960) has shown that hailstones may have unexpectedly large back‐scattering cross‐sections. In order to shed additional light on this problem, the normalized back‐scattering cross‐sections (σb) of spherical ice particles with complex index of refractionN= 1·78 – 0–0024i (N = m – mkiwheremis the ordinary index of refraction, andmkis the Mie absorption coefficient) were calculated from the complete Mie equations. Small intervals of α (= 2πa/λwhereais the radius of the scattering particle and λ is the wavelength of incident radiation) were taken up to a value of 30. The back‐scattering from large ice spheres is shown to be considerably higher than that from water spheres of the same size. In general, the differences between the reflectivities of ice and water spheres increase with increasing α up to an α of about 60.Calculations of (σb) were made for various values of the complex index of refraction in order to better understand the properties of the b

ISSN:0035-9009    

DOI:10.1002/qj.49708737210

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractA detailed discussion of the basic ‘black’ and ‘white’ sphere experiment designed by Suomi, and successfully launched in more elaborate form in Explorer VII in October 1959, is presented. It is concluded that this experiment is in almost every respect well suited for making heat‐balance measurements from a simple unstabilized satellite, but that it suffers from the serious disadvantage of any such system that the sampling rate is inadequate for giving the daily or short‐term heat balance of any region of the earth. Other main conclusions are: the magnitude of the possible error incurred by employing a spherical detector to measure the vertical intensity of a diffuse, anisotropic radiation stream is estimated to be a few per cent only; corrections for heat transfer by conduction and radiation to the spheres from the main body of the satellite can be reduced to negligible proportions, but heating due to high velocity impacts with gas molecules may be considerable for low orbits (0.16 cal cm−2min−1at 200 km); the time constant of the detector is shown to be not less than about two minutes; the sensitivity is of the order of 1°K per 0·01 cal cm−2min−1; the prospects of checking the calibration of the equipment in f

ISSN:0035-9009    

DOI:10.1002/qj.49708737211

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY