ENERGY FROM THE SUN Chapter 14.3 Pages 402-407
Energy in the Atmosphere • The sun is the source of ALL energy in our atmosphere. • Three things that can happen to energy from the sun: • Energy is reflected back into space. • Energy is absorbed by the atmosphere. • Energy is absorbed by land and water surfaces.
Energy that reaches Earth • Radiation: • The transfer of energy by electromagnetic waves. • Observed as light and heat • Flows from high temperatures to low temperatures • Ozone layer absorbs ultraviolet radiation from the sun
Conduction: • Transfer of energy when molecules touch. • The surface of the street is heated by radiation, but the air above the surface is heated by conduction because the molecule in the air touch the surface of the street and transfer energy into those molecules. • High energy, fast moving molecules transfer energy into lower energy, slower moving molecules.
Convection: • Transfer of heat by the flow of a heated material, such as a gas or a liquid. • Cold, dense air sinks forcing warm air up. As the warm air cools, it becomes more dense and sinks. This causes a convection current. Cold, dense air SINKS Warm, less dense air RISES
Water Cycle • Earth is the only planet where water exists in 3 forms: solid (ice), liquid (water), and gas (vapor). • 97% of water on Earth is salt water • 3% is fresh water • Sun provides the energy for the water cycle • All water on the Earth’s surface is part of the hydrosphere