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R = - (G + H + L ) |
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R = net solar and terrestrial radiation at the
earth’s surface (+ into surface) |
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Absorbed solar radiation (incoming – reflected) |
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Incoming longwave radiation emitted by gases and
clouds in the atmosphere |
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Outgoing longwave radiation emitted by the
earth’s surface |
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G- storage of energy into the deep soil (- into
soil) |
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H – heat flux into atmosphere(- into atm) |
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L – Latent heat flux into atmosphere ( - into
atm) |
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high
intensity of solar radiation at high altitudes can result in high surface
temperature |
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Austria- 80C humus at 2070 m; air temp at 2 m
30C |
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New Guinea 60C at 3480 m air temp 15C |
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Absorbed solar radiation depends strongly on
albedo: Abs Solar = Solar (1 – a) |
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Snow cover reflects solar radiation and
diminishes absorbed solar radiation |
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Annually, snow cover at high elevation later in
season than in valleys tends to cause absorbed solar radiation to diminish
with elevation |
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Stefan-Boltzmann Law: IR = esT4 |
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As elevation increases: |
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temperature decreases, IR radiation decreases |
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Optical thickness of atmosphere decreases (less
greenhouse gases, including water vapor), atmospheric transparency to
outgoing radiation increases, more IR escapes |
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Emissivity (e) of snow and ice is high |
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Net Radiation = Absorbed solar radiation +
downwelling IR – IR |
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Effect of altitude on net radiation is variable
and depends most strongly on decrease with height of absorbed solar
radiation |
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Small topographic irregularities |
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Differences in slope angle and aspect |
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Types (Turner 1980) |
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Sunny windward slope (high radiation; high wind) |
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Sunny lee slope (high radiation; low wind) |
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Shaded windward |
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Shaded lee |
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Notes