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

1.

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!!