THE author of these hundred pages addresses himself to the airman student who comes fresh to meteorology and has little knowledge of physics. That is not an easy task-no good elementary textbook is-and great success has not been achieved in this instance. Nevertheless, the author's aim is sound : to present a limited factual survey of the physics of the troposphere, the medium in which the student will in the main be flying, and, so that the book shall be more than an exercise of memory, to attempt some correlation of the facts themselves. No mathematics is used in the process.