EVPP 108 Lecture Notes - Lecture 7: Headache, Nitrogen Dioxide, Smog

• School: George Mason University
• Department: Environmental Science and Public Policy
• Course: EVPP 108
• Professor: Kim Largen

Document Summary

Early aquatic organisms started producing organic matter through photosynthesis. It saturated the water then started filling atmosphere. O2 was toxic to some primitive organism hence they perished. Other species started using o2 for getting energy through respiration. Between 1-2 billion years ago o2 built up in the atmosphere. Some o2 molecules were split by uv radiation to single atoms. It absorbs the harmful uv radiation coming from sun. Life form started from sea then moved to land. The present composition of atmosphere is same as it was 500 million years ago. Due to biological activities it is changing now. The physical parameter of the atmosphere vary with altitude. Temperature varies from -100 c to 1200 c. Atmosphere mass is very small compared to earth"s mass. It is the multilayer gaseous envelope that surrounds earth. It gives all the gases necessary for sustenance of all life forms in biosphere. It protects the earth from becoming too hot.