Temperature Changes in the Higher Atmosphere

UNTIL some years ago, it was generally thought that the temperature of the stratosphere was practically uniform, and of the order of 220° K. A radical change in such notions was first effected by Lmdemann and Dobson who, in 1922, from their study of meteor tracks, showed that the temperature at levels above 60 km. was even higher than that at ground-level. Their conclusions have been adequately confirmed recently in experiments on the anomalous propagation of acoustic waves, on the vertical distribution of ozone with height and, to some extent, by direct temperature measurements in high balloon ascents. There is, then, trustworthy evidence that solar radiation does not pass through the middle part of the atmosphere without warming it, so that we are led to examine, in this connexion, the evidence relating to still higher atmospheric levels, where such heating might be expected to be especially pronounced, since the solar radiation is there most intense and the thermal capacity of the transmission medium least.