Download File - Earth Science With Mrs. Locke

Heating the
Atmosphere
Of the energy that reaches us:
25% is scattered and
reflected into space
20% is absorbed by
clouds and gasses.
HALF is absorbed
by the ground to
heat Earth.
5% reflects off the
ground
The Earth gets
energy (heat)
from the sun by
RADIATION (=the
transfer of energy
through space as
electromagnetic
waves)
Although the sun radiates a huge amount of
energy, Earth receives only about twobillionths of this energy. But this small fraction
of energy is enough to drive the weather
cycle and make Earth habitable.
To heat the atm. energy is spread by:
1. Conduction: Energy Transfer by
Contact
the transfer of thermal energy through a material by
contact from warm to cold areas.
2.
Convection: En. Transfer by Circulation
– Most thermal energy is transferred this way
– Through convection currents, a cycle of warm air rising
and cool air sinking.
•
As air is heated, it becomes less dense and rises. Cool air is denser, so it sinks. As the cool air sinks, it
pushes the warm air up. The cool air is eventually heated by the Earth’s surface and begins to rise
again.
So to heat the air:
1 Radiation transfers en.
From sun to Earth
Finally convection currents
are created as warm air rises
& cool air sinks.
4
3
2
Some of the en. gets
absorbed by the surface
Conduction
returns the
heat to the air
Therefore
• The temp. of the air
depends A LOT on the
temp. of the surface below
it.