NATS 1840 Lecture 5: Sun and conditions
22 Feb 2019
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Document Summary
All of the energy available on earth comes to us from the sun. It started off as just hydrogen then it fuses and starts creating helium. The suns power output varies continuously, but with some regularity. 11 year sunspot cycle is correlated with solar output. Brightness (output) is on a long term increasing trend. Has probably risen by 25% since the protostar phase. When the supply of hydrogen to be burned runs out, the sun dies out and become a white dwarf in about 5 billion years. Lithosphere: solid rock crust floating on a liquid interior. Hydrosphere: temperature allows liquid water (71% of surface) The earth intercepts only a tiny fraction of the sun"s total power output: an average of about 1360 w/m^2 (the solar insolation) at the top edge of the atmosphere. Most of this energy is delivered in the form of visible light.
