ch 24.3 solar radiation, pressure, & wind. earth’s energy balance input = sun’s energy =...
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CH 24.3 Solar Radiation, Pressure, & Wind
Earth’s Energy BalanceInput = 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 ValuesSurfaces 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 BalanceOutput = 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 LoopsPositive 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 FeedbackIce melts Less energy reflected/more absorbed E. warms ice melts
Ch. 24.3 Energy Transfer in the Atmosphere1. 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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