Atmosphere, according to Alberuni, is that part of space which is just above the lithosphere. It is the envelope which covers the earth from all sides. He considers the atmosphere of great consequence to man because most of the meteorological phenomena occur there. He also finds a close relationship between the hydrosphere and the atmosphere and describes the lithosphere as the connecting link between these two,⁷⁸ meaning thereby that the heat of the Sun lifts up moisture from the sea, which is converted into vapours and these, in turn, become a part of the atmosphere where they move as moisture in the winds and when these winds and clouds pass over the elevated portions of the lithosphere, they are cooled down and precipitation in the form of water and snow takes place.⁷⁹

Alberuni does not throw any light upon the composition of the atmosphere. The only constituents of...