ISSN:0035-9009    

DOI:10.1002/qj.49707733302

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractMethods are described whereby 28 measurements were made of the rates at which cold air masses crossing the eastern North Atlantic were receiving heat and water vapour from the sea. It is shown that the rate of heat transfer is closely associated with the difference between the sea temperature and the surface temperature representative of the air mass, and some of the implications of this result are discussed.

ISSN:0035-9009    

DOI:10.1002/qj.49707733303

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractChanges in the physical properties of continental polar air are studied for air currents with trajectories over the Hudson Bay region. Computations indicate that westerly air streams crossing Hudson Bay in early winter are modified to a depth of 5 to 10 thousand ft. By midwinter, however, the modification is found to be negligible. This lack of modification in midwinter is attributed to the formation of an ice surface on Hudson Bay. Changes in the climate of the surrounding area caused by the formation of ice on Hudson Bay are illustrated by changes in temperature, cloud and snowfall. The modifying influence of the Bay in cooling the air in summer and heating the air in early winter is also discussed.

ISSN:0035-9009    

DOI:10.1002/qj.49707733304

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe profiles of temperature, humidity and wind have been determined by conventional methods in the lowest 2 m of the atmosphere above a close‐cut grass surface, with simultaneous observations of the heat absorbed in the soil and of the short‐wave and long‐wave radiative flux of heat. Twentynine sets of observations were made; the details are given in Appendix I.The ratio of the gradients of temperature and humidity is found to be independent of height, and changes with height of the vertical convective flux of heat and of water vapour are relatively small; the ratio of the coefficients of eddy diffusion of heat and water vapour is therefore independent of height. These coefficients are then assumed equal and the convective fluxes of heat and of water vapour determined (Bowen's method). The fluxes are also determined by an aerodynamic method which assumes equality of the eddy viscosity and the appropriate diffusion coefficient. The results of the two methods agree in most cases, in both stable and unstable stratifications, but there are some exceptions which cannot be explained.Absorption of radiation by the air is investigated. It is shown that this is comparable in effect with convection in the control of temperature and relative humidity. Particular attention is paid to four occasions with very light wind (including two with fog formation) when horizontal mixing appeared to be of major importance.Some examples are presented of wind profiles which do not conform to the law proposed by Deacon. A value between 0.5 and 1.5 is suggested for the critical Richardson n

ISSN:0035-9009    

DOI:10.1002/qj.49707733305

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe growth of unusually large cloud droplets by coalescence within isolated convective clouds is examined. It is found that if their initial radii are about 20 μ or more then growth into raindrops may readily occur. Raindrop nuclei of this size may be provided by spray in maritime air masses, but there is reason to suppose that in continental air masses droplets of the required initial size are not naturally introduced into the bases of convective clouds. Therefore the coalescence mechanism of precipitation release is probably effective only in maritime air masses. A condition for the production of a shower by the coalescence mechanism is obtained and applied to predict a minimum critical cloud depth of about 1.1/2 to 2 km. Showers may develop from clouds wholly below the 0°C isotherm if their base temperature exceeds about 8°C. A relation between the size of raindrops and the speed of the convective updraught is found, and an association is discovered between the non‐fulfilment of conditions for raindrop‐splitting within cloud and the absence of t

ISSN:0035-9009    

DOI:10.1002/qj.49707733306

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractExperimental data relating to drop‐size distribution in cloud and fog are examined and it is shown that in many cases the size distribution can be represented by the formula\documentclass{article}\pagestyle{empty}\begin{document}$$ 1 - F = \exp [ - (x/a)^n ] $$\end{document}whereFis the fraction of liquid water in the air comprised by drops with diameter less than x. The constantaincreases with the liquid water content of the cloud. It is not clear what governs the value of the constantnbut a reasonable mean value is about 3.3.It is shown that, if the drop‐size distribution can be described by the equation quoted above the median volume diameter is the most suitable parameter for describing the average size of the cloud particles when the value ofnis not kn

ISSN:0035-9009    

DOI:10.1002/qj.49707733307

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractTwo years of upper‐air data from the four daily radiosonde ascents from five stations in the British Isles are analysed for the pressure levels 150 mb, 100 mb and 80 mb ‐ some 14,000 ascents in all.The apparent diurnal temperature changes are discussed and the need is shown for further experimental evidence concerning the reality of the measured high‐level daylight temperatures. The observed daylight heating is too great to be caused by the absorption of radiation and must either be dynamical in origin or due to radiation error of the thermometer element in the radiosonde. From 1948, the times of ascent are suitable for computing thenocturnalcooling throughout the year, independent of radiation error. The temperature falls during the night by about 0.05°C hr−1at these levels, the sort of change to be expected if radiative processes predominate.The apparent rate of change of temperature closely following sunrise and just preceding sunset is about ten times more rapid than the nocturnal cooling.It is concluded that the amplitude and rate of the apparent variations of temperature measured in daylight ascents should be treated with reserve until further experimental evidence as to their reality is a

ISSN:0035-9009    

DOI:10.1002/qj.49707733308

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe mean 500 mb contour patterns and 1,000‐500 mb thickness patterns for the northern hemisphere in January and July are examined. The orographic‐dynamical hypothesis advocated by Bolin (1950) is considered. A thermal‐synoptic explanation, resting mainly on the direct thermal effects of land and sea modified by baroclinic synoptic processes, is regarded as satisfa

ISSN:0035-9009    

DOI:10.1002/qj.49707733309

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe size distribution of water droplets in thin stratocumulus cloud has been investigated using an impactor technique. The variation from point to point in the cloud is considered and it is shown that where the water content is large there is generally a larger number of particles but the average size is also greater. It is remarked that it seems to be quite usual for this sort of cloud to have a double maximum in the size distribution of droplets.

ISSN:0035-9009    

DOI:10.1002/qj.49707733310

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractA simple form of raindrop spectrograph is described. It is capable of giving a continuous record of the changes in the distribution of drop sizes which occur during a fall of rain.Examples are given of the spectra obtained during a variety of rain situations ranging from continuous rain to isolated showers.

ISSN:0035-9009    

DOI:10.1002/qj.49707733311

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY