class5_w08

class5_w08 - Radiation balance for Earth 100 units...

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Radiation balance for Earth Global albedo of 30% - reflection by clouds + reflection by atmosphere + reflection from Earth surface Absorbed by Earth (heating Earth) – 44% Absorbed by atmosphere (heating atmosphere) – 26% Albedo : % of reflected radiation from Earth’s surface – varies widely from 2-90% 100 units corresponds to 54.4 x 10 20 kJ/yr
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Radiation balance for Earth Maintain energy balance – 70% of input solar energy (that is not reflected) must be radiated out (at IR wavelengths) Because of the greenhouse effect, more energy is in circulation in the outgoing IR – absorbing gases (H 2 O, CO 2 , etc) reradiate in all directions (Earth emits 115 units; heat balance requires 70 units output) Heat balance on the atmosphere Influx of solar energy minus reflection
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Albedo – influence on heat balance Varies greatly over the Earth’s surface -as low as 6% in the oceans (most energy absorbed) -agricultural and forest land are low albedo (10-20%) -deserts are higher (25-40%)
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This note was uploaded on 08/06/2008 for the course CHEM 123 taught by Professor Perona during the Winter '08 term at UCSB.

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class5_w08 - Radiation balance for Earth 100 units...

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