Rainless Thunderstorms

Abstract

FROM the letter signed “E. G.” in your issue of August 31, it would appear that the Meteorological Office has not abandoned the ion condensation theory of the origin of atmospheric electricity. Now, there are many difficulties in accepting that theory. For instance, before condensation can take place on ions, there must first be dustless air; otherwise the necessary supersaturation cannot take place; and one naturally asks, Has anyone ever found dustless air in our atmosphere? So far as records go of air up to 10,000 feet, this has not yet been found, and it does not seem likely that it ever will be found, as the hot air carrying up the aqueous vapour to form clouds always carries up with it plenty of dust to act, if one may use the simile, as the return ticket to bring the water back to the surface of the earth. As much of this dust is very fine, only falling a few centimetres in a day at low level, it is likely to go wherever the moist air goes—in even the more rarefied regions of the upper clouds. Further, there is the constant supply of fine dust from the upper regions due to the disintegration of meteors, so that the air at cloud levels is likely always to have plenty of dust and condensation on ions seems impossible.