ISSN:0035-9009    

DOI:10.1002/qj.49707632702

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractFrom a knowledge of the three‐dimensional wind field as a function of space and time, the total wind acceleration and the trajectory curvature can be computed, permitting the evaluation of the geostrophic wind vector without recourse to analysed isobars or height contours.A study of 618 cases at 10,000 ft for a 3‐day November sequence, using observed winds over the North American continent, revealed that the mean absolute angle between the reported wind and the geostrophic wind directions was approximately 15°. Large deviation angles were associated with low geostrophic wind speeds, and thus indirectly with low latitudes. The corresponding mean cross‐isobar wind component was slightly greater than 5 mi hr−1. The mean absolute deviation between wind and geostrophic wind speeds was of the order of 7 mi hr−1, the corresponding mean relative deviation being just under 30 per cent. Large relative deviations were associated chiefly with low geostrophic wind speeds, hence indirectly with low latitudes.The mean total wind acceleration slightly exceeded 40 mi hr−1day−1. The mean trajectory curvature corresponded to a radius of curvature of 175 mi. It was found that the mean components of these terms associated, formally, with horizontal and vertical advection were virtually identical in magnitude, illustrating the importance of the vertical velocity contribution to wind accelerations and curvatures. The mean local tendency component was numerically smaller than the two advective terms in the care of accelerations, but numerically larger in the case of traject

ISSN:0035-9009    

DOI:10.1002/qj.49707632703

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractExperimental data relating to drop size distribution in rain are examined and it is shown that in many cases the size distribution is in accordance with the following formulae 1 ‐F= exp [‐(x/a)n]a= A IpW = C IrwhereF= fraction of liquid water in the air comprised by drops with diameter less than x.I= rate of precipitation.W= amount of liquid water per unit volume of air.A, C, p, rand n are constants. If × is measured in mm,Iin mm/hr andWin mm3/m3the mean values ofA, C, p, rand n are 1.30, 67, 0.232, 0.846 and 2.25 respectively. There may be appreciable variations from these mean values, particularly in the case of n, if the precipitation is essentially of a showery or orographic nature. Tables based on these formulae are given showing values ofWand of the number and total volume of drops between certain diameter limits for various rates of rain

ISSN:0035-9009    

DOI:10.1002/qj.49707632704

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractAn account is given of further measurements of atmospheric radiation which confirm former conclusions regarding the errors of two types of radiation chart when used to compute total radiation at the surface. The greater part of the difference between computed and observed radiation is attributed to two causes – emission from particulate matter and the variation of emissivity of water vapour with temperature. The results suggest a form for this variation between −5°C and +25°C.Some measurements and computation of the change of radiative flux in the lowest metre at night, i.e., of the direct radiative cooling of the air, are reported. Miscellaneous subjects discussed include the radiation from atmospheric dust, the radiative temperature of a short grass surface and its measurement by simple means in all conditions, and an anomalous occasion with very high incoming radiation for which no explanation could be found. Some comments are offered on the experimental justification of two possible uses of the radiation c

ISSN:0035-9009    

DOI:10.1002/qj.49707632705

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractCalculations are made from which it appears that the rate of loss of heat from ice particles growing by coagulation in dense supercooled clouds may be insufficient to allow all the acquired water to freeze. The larger coagulation‐elements within cumulonimbus clouds may therefore have liquid skins at levels where the temperature has fallen to −20° or −30°C. The rain‐drop multiplication process envisaged by Langmuir may thus proceed also at temperatures well below 0°C, and the effect may also be important in the production of ice nuclei by‘splinter’ formation and in the generation of thundersto

ISSN:0035-9009    

DOI:10.1002/qj.49707632706

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractDuring the last decade many experiments have been designed to investigate the initial processes of ice formation in the atmosphere. The results of these experiments are examined for clues as to the identity of the responsible nuclei and the following tentative conclusions are reached: (a) The nuclei which cause freezing between 0°C and −32°C are mainly solid, insoluble particles which are wetted by water and produce ice particles through the freezing of water drops.(b) The nuclei which become operative in the range −32° to −11°C consist of droplets of sea salt solution, ice and salt crystallising out on contaminating foreign particles at a temperature depending on the efficiency of these particles and the rate of expansion of the ambient air.(c) The nuclei effective at just below −41°C consist of droplets ofpuresalt solution and possibly of “ gaseous” nuclei formed industrially or by the action of ultra‐violet light on the gases of th

ISSN:0035-9009    

DOI:10.1002/qj.49707632707

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractThe accelerations observed during the flight of seven constant‐height balloons are examined.These observations extended over periods of 2 to 4 1/2 hr. It is found that the values of the geostrophic departures determined from the accelerations are closely comparable with the values deduced independently from contour charts and observed winds.The variations in the acceleration are greater than would be expected from errors in wind determination alone; it is deduced that this is due to the wind at the level of flight being affected by eddies giving rise to fluctuations of the order of 3 to 4 kt in the value of the mean wind determined over half‐hour interv

ISSN:0035-9009    

DOI:10.1002/qj.49707632708

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractGrimes (1937) made a first essay to treat the passage of air across the equator dynamically. His work has been extended by Crossley (1948). In the present paper a flow pattern is presented which proves not intractable in spherical polar co‐ordinates in the equatorial belt. Frictionless horizontal flow is considered and it is shown that clockwise and counter‐clockwise circulations can exist in equilibrium on the equator. The centre of the pressure field is displaced into the hemisphere for which the circulation is cyclonic and both circulations thus appear as cyclones. It is found that trajectories and contours pass freely across the equator but that the relation between winds and contours is varia

ISSN:0035-9009    

DOI:10.1002/qj.49707632709

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractVisual and photographic observations of the illumination of the sky‐sea horizon, made in light of different wavelengths, indicate an enhanced brightness contrast when the shorter wavelengths are excluded. The effect is most pronounced in the presence of haze, or light mist. When use is made of an analysing filter to modify the relative amounts of polarised light received from sky and sea, the degree of contrast obtainable depends on a number of independent factors,e.g., amount of cloud cover, and state of sea surface that may, or may not, combine to give better visibility of the sky‐sea boundary. Anomalous polarisation effects are frequently observed during early twilight along the anti‐solar path. This work was carried out while with the Kodak Research Laboratories. The paper is issued as Communication No. 1263H from the Kodak Research Laborat

ISSN:0035-9009    

DOI:10.1002/qj.49707632710

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractUsing the observational material presented in an earlier paper (Miles 1949) it is found that the following relation fits the observations ahead of most of the warm fronts : [A] = 1.45IM– 1, where [A] is the magnitude of the ageostrophic wind at 900 mb andIMthe measured isallobaric wind as defined by Brunt and Douglas (1928), both in mi/hr.It is shown that when allowance is made for the fact thatIMis obtained from isopleths drawn from three‐hour tendencies the result compares closely with other observational relations which have been shown (Miles 1949) to be in agreement with theory.This and some further measurements from synoptic charts lead to the conclusion that in the majority of cases the measured isallobaric wind can give a useful first approximation to the ageostrophic wind at 900

ISSN:0035-9009    

DOI:10.1002/qj.49707632711

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY