GEO 101 Lecture Notes - Lecture 20: Halocarbon, Positive Feedback, Milankovitch Cycles
15 Nov 2016
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Document Summary
Greenhouse effect of earth"s atmosphere keeps earth at habitable temperatures. Albedo: reflectivity of surfaces: high albedo surfaces reflect sunlight as short wavelength visible light, low albedo surfaces convert sunlight to long wavelength infrared radiation, which emits heat. Greenhouse gases are transparent to short wavelength visible from the sun but block long wavelength infrared radiation from the ground. Methane and carbon dioxide are 2 largest greenhouse gases, carbon dioxide. *absolute test question: halocarbon cfcs, ozone o3, nitrous oxide. Air make-up: nitrogen 78. 08, oxygen 20. 95, argon 0. 93, water vapor variable, trace gases. 100,000-year ellipticity cycles couple with changes in greenhouse gas levels and positive feedback mechanisms to cause glacial periods and interglacials: original little warming gets warmer and warmer and so on. Feedback mechanisms: positive feedback mechanisms result in runaway effect. Push of variable in one directions results in additional impetus in same direction, to greater and greater effect.
