GEOG 2050 Chapter : Chapter 3
Document Summary
Weakly bounded by gravity as far as 32,000 km from earth: we have an atmosphere is because of gravity. Air pressure: earths atmosphere exerts its weight, pressing downward due to gravity, air molecules create air pressure through motion, size, and number. 29. 92 inches of mercury (hg) measured by a barometer. Atmospheric composition: the atmosphere is divided into 2 broad regions, the heterosphere and the homosphere, homosphere, exists from the surface to 80 km altitude, gases are well mixed. The ozone layer is located from 19 to 50 km: vast reservoir of nitrogen, heteropshere, exists between 80 to 480 km altitude, lighter gases that aren"t evenly mixed, makes up less that 0. 001% of the atmosphere"s mass. Chemical composition: major gases, nitrogen (n2): 78% is from volcanic activity, oxygen (o2): 21% is from photosynthesis, argon (ar): 0. 9% is from radioactive decay of potassium, carbon dioxide (co2) is 0. 037% is a natural life by-product.
