This booklet is the fifth in a series of nine that describe the Apollo-Soyuz mission and experiments. This set is designed as a curriculum supplement for high school and college teachers, supervisors, curriculum specialists, textbook writers, and the general public. These booklets provide sources of ideas, examples of the scientific method, references to standard textbooks, and descriptions of space experiments. There are numerous photographs and diagrams, as well as questions for discussion (with answers) and a glossary of terms. This pamphlet discusses observations of the earth's surface from space, aerosols that affect climate and weather on earth, and the oxygen and nitrogen in the outer atmosphere. (MA)