ISSN:0035-9009    

DOI:10.1002/qj.49707733102

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49707733103

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractA description is given of observations made in south‐east Australia of medium and heavy rain falling from clouds which were everywhere warmer than 0°C. Detailed observations were made visually from aircraft and these were supplemented by measurements of the radar echo intensities and drop size spectra within the clouds.The clouds were all deep cumulus and were over or near the sea. Great concentrations of relatively large water drops were observed in the upper levels of the clou

ISSN:0035-9009    

DOI:10.1002/qj.49707733104

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractA pilot study of the horizontal eddy transport of angular momentum in the meridional direction, based on radio wind observations over the North American sector of the northern hemisphere, is presented. The results are in harmony with general frictional requirements except that the transports are rather large. The desirability of much more extensive compilations of data concerning the subject is indicated.

ISSN:0035-9009    

DOI:10.1002/qj.49707733105

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractIt is shown, on the basis of about 700 measurements made at a particular station during six months, that the thermal change in the troposphere due to advection alone is largely offset by the other processes at work, so that the resultant change is a residual having a correlation of about 0.6 with the advective component.The shear hodograph of an upper wind sounding is shown to afford little useful information on the resultant thickness tendency.

ISSN:0035-9009    

DOI:10.1002/qj.49707733106

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractA definition of convective vertical heat flux is proposed which leads directly to the expressionp1w1h1wherep1,w1, andh1are, respectively, simultaneous values of the fluctuating density, vertical velocity relative to the surface, and total heat per unit mass at a point in a constant pressure surface. Neglect (apparently justifiable) of the pressure fluctuations yields the expressioncpp±w1/Rfor the convective flux of sensible heat. The distinction between free and forced convection is made. Recent treatments by Montgomery and by Priestley and Swinbank are examined with particular attention to the importance of free convection. It is submitted that neither Montgomery's neglect of the buoyancy forces nor Priestley and Swinbank's arguments suggesting their universal importance can at present be justified. In particular the latter authors explanation of the normal tropospheric lapse rate is questioned

ISSN:0035-9009    

DOI:10.1002/qj.49707733107

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49707733108

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe equation governing the behaviour of two‐dimensional waves in a horizontal stably stratified shearing air current is set up. It is shown that it may be obtained by considering the limit as the number of a set of superposed statically‐neutral layers, each of constant stream velocity, tends to infinity, but that the properties may differ considerably if the number of layers is few.If stable waves occur then at no level do they travel with the same velocity as the air. If unstable waves occur the surfaces containing the wave crests may be so inclined to the vertical as to limit the growth of the waves. Some remarks are made concerning the difficulties of discussion of unstable waves in the general c

ISSN:0035-9009    

DOI:10.1002/qj.49707733109

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractRaindrops were admitted by a cone‐shaped opening into an insulated vessel connected to a valve amplifier for measuring the drop chargeQ.Drop radius a was found by the absorbent paper method. The field at the ground and the point discharge currentIwere also measured. Most often, but not always, the signs of the drop charge and field were opposite. During point discharge, 173 drop charges and masses were measured, and statistical analysis showed a definite correlation betweenQandI—, a probable correlation betweenQ/—I andaand a possible correlation betweenaand —Q. By grouping drops according to radius, and taking averages within the groups, the approximate relationshipQ/—I ∞ a was obtained. In one period when the radius was nearly constant, the observations gave the connectionQ∞ —Iwithout taking averages. The observed relation betweenQandIcorresponds to the results of Simpson (1949) for the charge on a volume of rain. The observed charges were mostly much higher than predicted on Wilson's ion‐capture theory, unless the field increases considerably with height

ISSN:0035-9009    

DOI:10.1002/qj.49707733110

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractFifty cold fronts are classified by means of two simultaneous aerological soundings. Two general categories are found:(1)Those in which the warm air is descending, usually forming a subsidence inversion. The nameKatafront(following Bergeron) is applied to such fronts.(2)Fronts at which the warm air is ascending. These, which are namedAnafronts, usually show no sharp discontinuity on a tephigram.The two types of cold front give rise to quite different weather conditions. The changes in wind and temperature are generally much more abrupt at an anafront, where there is also much more precipitation. A katafront frequently brings a rapid clearance followed by fine weather.The variation of wind with height through the front is markedly different at the two types, the chief characteristics being:Anafront: Rapid backing of wind with height; the component normal to the front decreases. The upper winds are inclined at a small angle (about 15°) to the line of the front.Katafront: Slight backing with height; the normal component increases considerably. The upper winds are inclined at a large angle (about 40°) to the front. Consideration of the horizontal wind changes across the front leads to the expectation of troughs with strong cyclonic shear at anafronts, and the more rapid occlusion of katafronts.Anafronts and katafronts are generally associated with different stages in the history of a cold front; an anafront is normally the initial state, but develops into a katafront later as the depression becomes more occluded. Katafronts are the more common type in this country, especially in summer.Calculations of the mean slope above the friction layer give values of about 1/70 for anafronts, and 1/300 for katafronts. The vertical velocity of the warm air at an anafront is of the order of 10 cm/sec upwards, while at a katafront it is about 2.5 cm/sec downwards. Vertical cross‐sections of wet‐bulb potential temperature show that there is often latent or convective instability at the nose of a katafront. This may be the explanation of the large ascending velocities found in this region by sailplane p

ISSN:0035-9009    

DOI:10.1002/qj.49707733111

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY