http://www.andor.com/image_lib/lores/introduction/introduction%20(light)/intlight%201%20small.jpg

http://lasp.colorado.edu/cassini/images/Electromagnetic%20Spectrum.jpg

Energy

All matter above 0K emits Rn in the form of waves

Some objects absorb and emit Rn in certainonly

The of Rn emitted by a surface depends on the temperature (Wien’s Law):

max =

w = constantT = temperature

wT

Energy

The higher the temperature of an object, the greater the rate/intensity of Rn emission (Stefan-Boltzmann Law):

E = T4

E = maximum rate of Rn/second = constantT = temperature

Energy

The amount of Rn striking a surface is inversely related to the square of the distance from the source:

1d2

Energy

• Solar constant 1367 W m2 s-1

Absorbed

Scattered

Reflected

Energy

THE GREENHOUSE EFFECT

Some solar radiationis reflected by the Earth and atmosphere.

Solar radiationpasses throughthe clear atmosphere.

Most radiation is absorbedby the Earth’s surface and warms it.

Infrared radiation is emitted from the Earth’s surface.

Some of the infraredradiation passes throughthe atmosphere, and someis absorbed and re-emittedin all directions by greenhousegas molecules.

The effect of thisis to warm the Earth’s surface and lower atmosphere.

EARTH

ATMOSPHERE

Energy

Energy

Energy

Energy

i = S(1 – )

i = long-term input, S = solar flux,and = albedo

Radiative equilibrium temperature

S