The Earth’s atmosphere and its interactions with cryosphere is presented. The text begins with introducing the basic atmospheric variables and their distributions with elevation followed by solar and terrestrial radiation. Then the surface mass balance is introduced, particularly the formation of snow crystals and snowfall. The last section presents the basic atmospheric boundary layer physics and surface heat balance. After carefully reading this chapter, a student can comprehend the importance of the atmosphere for cryosphere and solve the snow an ice physics problems in the chapters to follow.