Abstract
LONDON. Royal Meteorological Society, May 20.—Sir Gilbert Walker: Recent work by S. Mal on the forms of stratified clouds. Two years ago it had been suggested that the breaking up of a stratum of cloud into polygons or long strips was often due to instability, accompanied in the latter case by shear parallel to the strips. Mal showed that a rectangular pattern was caused when the unstable stratum was subjected to a less rapid shear than is needed for strips; and verified from measurements made in the sky that cloud strata break up or persist according as their temperature gradient is unstable or stable; and that when they break up the pattern assumed is polygonal, rectangular, or in strips according as the shear is zero, moderate, or large.—C. K. M. Douglas: A problem of the general circulation. So far as can be judged from present data, there is no appreciable net flow of polar air in the lower troposphere towards the subtropical anticyclone. This supports the view of Dr. Jeffreys, namely, that the exchange of air between different latitudes, required to maintain the angular momentum of the zone of west winds against friction, is carried out entirely by currents lying side by side, and not one above the other. The fundamental problem is the relation of the individual cyclone to the general circulation, and this has not yet been solved.—G. S. P. Heywood: Wind structure near the ground, and its relation to temperature gradient. The wind velocities were obtained by two anemometers at heights of 12.7 m. and 94.5 m. above the ground. There are not many results from anemometers so high as 95 m.; for this reason, the ordinary diurnal variation at this height in summer and winter is shown, with that at 13 m. for comparison. The vertical gradient of temperature up to 87 m. is also recorded. Wind gradient must depend largely on temperature gradient, and the relation between the difference in wind velocity and the difference in temperature over approximately the same height interval, is worked out for various wind strengths.
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Societies and Academies. Nature 127, 877–879 (1931). https://doi.org/10.1038/127877b0
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DOI: https://doi.org/10.1038/127877b0