Misti and its Cloud

Abstract

IN NATURE, vol. xii. p. 487, Mr. Stevenson gives an interesting example of the genesis of clouds, due to hills of about 900 feet high. Something similar is well known to the inhabitants of Arequipa, Peru. The city is built at the base of the extinct volcano “Misti,” which rises above the plaza of Arequipa to a height of about 12,500 feet; Arequipa itself being over 7,000 feet above the level of the sea. It is not an uncommon occurrence (during the fall of the year, February and March) in the morning, from sunrise till about ten o'clock, to see a succession of clouds rolling along the summit from N.E. to S.W., much as if huge masses of white smoke were issuing from the extinct crater. These clouds are either suddenly shot upward by meeting the current from the S.W. and lost at a distance of from 30,000 to 40,000 feet to the eastward from the summit, or else, rolling over the summit, they are carried by the easterly breezes till they become absorbed by the dryer and warmer air of the region to the southward of Misti.