# CH 24.3 Solar Radiation, Pressure, & Wind. Earth’s Energy Balance Input = Sun’s Energy = (Visible light + some UV) REFLECTED: ~ 25 % by clouds, dust,

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CH 24.3 Solar Radiation, Pressure, & Wind

Earth’s Energy Balance Input = Sun’s Energy = (Visible light + some UV) REFLECTED: ~ 25 % by clouds, dust, & gases ~ 5 % by surfaces ABSORBED: ~ 20 % by clouds, dust, & gases ~50% by surfaces Surfaces Matter! Albedo = measure of how much solar energy a surface reflects. Ice caps and clouds have a high albedo. Positive feedback loops: More ice caps --> more solar energy reflected --> cooler --> more ice caps Big Idea: Most air is NOT heated by the sun directly.

http://www.the-m-factory.com/portfolio/all_images/ill_maps-Albedo-Effect.jpg Ch. 24.3: Albedo Values Surfaces Matter to Earth’s Energy Balance Question: As icecaps melt, how will Earth’s albedo change? How will this affect climate? Why?

Earth’s Energy Balance Output = Energy Reflected from Earth back to space (Usually Infrared - longer wavelength) Greenhouse Gases: CO2, CH4, H2O Allow Visible light & UV to pass through, but Reradiates I.R. back to surface instead of letting it escape into space. More GHG = more I.R. = Warming Temps. Surfaces reradiate the solar energy that was absorbed by releasing longer wavelengths of I.R. (heat) Most of this I.R. escapes into outer space. Big Idea: The amount of reflective surfaces and the amount of GHG can have a big impact on TEMPS.

Feedback Loops Positive Feedback: a change causes a process to continue (amplify response) Negative Feedback: a change causes a process to stop (supression) A.Warming temperatures cause ice caps to melt. Discuss how this is a “feedback loop” B. Discuss how Snowball Earth came about through positive feedback

FEEDBACK = PROCESS THAT AMPLIFIES OR SUPPRESSES SOME INITIAL CHANGE. Examples: Positive Feedback Ice melts  Less energy reflected/more absorbed  E. warms  ice melts

Ch. 24.3 Energy Transfer in the Atmosphere 1.Radiation: Energy travels as a wave on the EMS. UV & Vis. Light from sun absorbed by surfaces Infrared (IR) waves are radiated from surfaces & heat air 2. Conduction: Heat energy is transferred by molecule collisions w/in a few feet of E’s surface. Requires contact b/w molecules. 3. Convection: Air masses transfer heat by moving. Warm, less dense air masses rise; Cooler & denser air masses sink... Convection Current or Cells. VERY IMPORTANT TO WEATHER & CLIMATE.

Heat Transfer

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