The Cause of Anticyclones

Abstract

IN a letter to NATURE of December 23 (vol. 110, p. 845) Mr. W. H. Dines has raised certain questions connected with the cause of anticyclones. The chief observational facts to be explained are the features peculiar to most high pressures, namely, the warm troposphere, the high and cold stratosphere. But not all anticyclones are warm even from a height of 3 km. up to 8 km. Some are cold to considerable heights. The gradual rise of the coefficient of correlation between pressure and temperature at the same level as one proceeds from 0 to 4 km., and the comparative uniformity of the coefficient from 4 to 8 km., is in itself strong evidence that in our latitudes these first 4 km. are the theatre of changes of air more and more frequent as the surface is approached, and that in the regions above 4 km. the air is nearly always of one sort as regards its origin. Again, with regard to persistence, Hanslik pointed out that only the “warm” anticyclones are steady and slow moving; the “cold” ones move quickly. Further facts to be taken into account are, that the conception of an anticyclone as a region of great vertical stability and of fine bright weather appears to be correct as a rule only for the “warm” anticyclone. In the other type anything short of violent weather conditions may be experienced.