GG 140 - Lecture 2 - Retaining an Atmosphere
Lecture 2 - Retaining an Atmosphere
There are other ways in which we can perceive the existence of the atmosphere, predominantly through our perceptions of pressure. Not all planets have atmospheres, and the existence of an atmosphere depends on the ability of gas molecules to remain trapped close to a planet by its gravitational force. The molecular velocity of each gas molecule depends upon its molecular weight, and must exceed the escape velocity of the planet to leave the atmosphere.
Essentials of Meteorology, Ch. 1