Solar Radiation and Insolation
Incoming solar radiation:
Intensity of radiation =
X = wavelengthY = temperature
Inverse relationship: The higher the
temperature the shorter the
wavelength of radiation.
X
Y Insolation is… ADD HERE
The intensity of insolation from the Sun on a specific area of Earth is dependent on a
number of factors.
Effects of Earth’s Atmosphere on Insolation
Ozone
Ozone
Nearly all ultraviolet (short wave) radiation is
ABSORBED by ozone (O3 gas) in Earth’s upper
atmosphere.
H20 vapor, methane and CO2 can ABSORB infrared (long wave)radiation.
Much of the incoming solar radiation is REFLECTED or SCATTERED back into space, into the atmosphere or to Earth.
Aerosols --solids and liquids in the atmosphere – ie: pollutants, dust , ice, ash, water droplets, etc.. cause this scattering of radiation.
Balance of Energy from Insolation and Earth’s
Surface Radiation
Nearly 50% of insolation reaches Earth’s surface.
Nearly 50% of insolation is absorbed or reflected by the atmosphere.
Insolation received by the Earth’s surface is changed to heat energy. The Earth’s radiates this heat energy back into the atmosphere.
The amount of energy absorbed from insolation = Earth’s surface
radiation.
Factors Affecting Absorption and Reflection of Insolation
Angle of IncidenceThe angle of
incidence is.. ADD HERE
The higher the angle of incidence = ADD HERE
The lower the angle of incidence = ADD HERE
Sun is high in the sky Sun is low in the sky
Factors Affecting Absorption and Reflection of Insolation
Surface Characteristics ADD HERE…
Rough, uneven surfaces and/or dark surfaces
absorb more insolation.
Light and smooth surfaces tend to
reflect rather absorb insolation.
Factors Affecting Absorption and Reflection of Insolation
Change of State and Transpiration
Insolation may cause a change in phase for water.
Insolation may fuel plant growth and increase the rate of
transpiration -- the process whereby a plant releases water
vapor into the atmosphere.
In both cases… ADD HERE
Land vs. Water Heating
Equal areas of land and water do not heat up and/or
cool off at the same rate.
Water is transparent and allows a greater
area for insolation to penetrate
compared to a land surface.
Water has a higher specific heat than
the land.
Convection currents in water allow for the distribution of energy absorbed
through insolation over a large
volume.
Some of the insolation striking the water may lead to a phase change
(evaporation). The energy from insolation is transformed to potential
energy.
The Greenhouse Effect
1. Short wave insolation… ADD
HERE
2. The Earth’s surface reradiates the energy absorbed… ADD HERE
3. “Greenhouse gases” in the
atmosphere… ADD HERE
4. The absorption of this radiation…
ADD HERE
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2.
3.
4.
The Greenhouse Effect
Modern history has shown an increase in the amount of “greenhouse gases” in
the atmosphere.
This increase is due primarily to human activity, such as the burning of fossil fuels and
emission of pollutants in to atmosphere.
The increase in “greenhouse gases” has led to an increase in
the amount of radiation absorbed from the Earth. This, in turn, has led to an increase in
average global temperatures. Result? Melting ice caps!!