Chapter 3Energy Balance & Temperature

What is main source of energy for atmosphere?

What happens to incoming solar radiation?

absorption

absorptiontransmission

absorptiontransmission

scattering

True or false?A. Gases in the atmosphere are

equally effective at absorbing sunlight.

B. Different wavelengths are equally subject to absorption.

C. UV is almost totally absorbed by ozone in the stratosphere.

D. Visible radiation is almost entirely absorbed by the atmosphere.

Absorption vs scattering

Why is the sky blue?

Why does the atmosphere look blue when viewed from space?

Why are sunsets red?

Q:

Which type of scattering is caused by larger aerosols and affects longer wavelengths?

A. MieB. RayleighC. Nonselective

Scattering summary

Rayleigh Mie nonselective

short wavelengths long wavelengths no preference

small particles larger particles water particles

scatters all directions mostly scatters forward

scattering by internal reflections in H2O

drops

why the sky is blue makes sky hazy optical effects (rainbows!)

energy balance

what goes in must come out

only 54% of photons at top of atmosphere actually reach the surface

albedo

the fraction of incoming radiation that is reflected back to space:● 25% clouds & gases● 5% surface

planetary albedo=30%

Annual average surface albedo

cartoons!

energy balance

energy balance

Which statement is false?

A. The Earth’s surface acts nearly as a black body.B. Radiation emitted by Earth is in the infrared portion of

the spectrum.C. Radiation emitted by Earth is shortwave.D. Some of the radiation emitted by the surface of the

Earth is absorbed by the atmosphere, some escapes to space.

atmospheric window

Photons are emitted by the earth.

Some are absorbed by atmosphere.

Some escape!

Atmosphere is transparent to shortwave radiation, but opaque to

longwave radiation.

HUH?

equilibrium temperature of the earth

energy balance

energy in = energy out

(assume no atmosphere)

Greenhouse effect!

Role of atmosphere

latitudinal variations in radiation

diurnal variations in temperature

diurnal variations in temperature

how do clouds affect this picture?

clear sky

cloudy sky

How can clouds act to both warm and cool the surface?

other types of heat transfer

Which has a higher specific heat?

A. oceanB. land