The Amateur Scientist; April 1998; Scientific American Magazine; by Carlson; 2 Page(s)

Every creature on the earth lives under the warm, nurturing and protective blanket formed by the atmosphere. Yet all this air does more than trap the sun's heat and carry gases between plants and animals. It also presses down on our world with powerful force. At sea level, a single sheet of writing paper, when laid flat, sustains 6,111 newtons--about 1,400 pounds.

One might imagine that such a burden would stress living creatures enormously. But far from hurting organisms, the weight of the atmosphere proves absolutely essential for life. Liquid water could not exist on the earth were not atmospheric pressure sufficient to keep it from boiling rapidly away. And many vital biological processes, cellular respiration chief among them, fail if the air pressure falls too low.