Heating the Atmosphere

Of the energy that reaches us: 20% is absorbed by clouds and gasses. 25% is scattered and reflected into space 5% reflects off the ground HALF is absorbed by the ground to heat Earth.

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 two-billionths 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: Conduction: Energy Transfer by Contact the transfer of thermal energy through a material by contact from warm to cold areas. 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 4 3 2 Radiation transfers en. From sun to Earth Finally convection currents are created as warm air rises & cool air sinks. 4 3 Conduction returns the heat to the air 2 Some of the en. gets absorbed by the surface

Therefore The temp. of the air depends A LOT on the temp. of the surface below it.