EARTH’S ENERGY

Energy from the Sun• Nearly all of Earth’s

atmosphere energy comes from the sun as electromagnetic waves.

• Most of the energy comes from the sun reaches Earth in the form of visible light and infrared radiation, and a small amount of ultraviolet radiation.

Visible Light

• Visible light is a mixture of all of the colors that you see: red, orange, yellow, green, blue, and violet.

• Different colors are a result of different wavelengths.

• Red and orange have long wavelengths while blue and violet have shorter wavelengths.

Infrared Radiation

• Wavelengths are longer than red light.• It is not visible, but it can be felt as heat.

Ultraviolet Radiation

• Wavelengths are shorter than violet light.• Can cause sunburns as well as skin

cancer and eye damage.

Energy in the Atmosphere

• Most of the energy that keeps Earth warm comes from the sun.

• Some of the energy is reflected and absorbed in the atmosphere.

• The rest of the energy reaches Earth’s surface, where it is reflected or absorbed.

Energy at Earth’s Surface

• When Earth’s surface is heated, it radiates some of the energy back into the atmosphere as infrared radiation.

• The energy from the absorbed radiation heats the gases in the air.

• These gases form a “blanket” around Earth that holds heat in the atmosphere, which is called the greenhouse effect.

Heat Transfer

• Some energy is transferred from the surface to the atmosphere in the form of heat.

• Temperature- is the average amount of energy of motion of each molecules of a substance.

• The energy transferred from a hotter object to a cooler object is referred to as heat.

• Heat transfers in three ways: radiation, conduction, and convection.

Radiation

• Transfer of energy by electromagnetic waves.

• You can not actually see the heat but you can feel it through infrared radiation.

Conduction

• The direct transfer of heat from one substance to another substance that it is touching.

• Ex. Walking on hot sand.• Conduction works well in some solids,

such as metal, but not as well in liquids and gases.

• Air and water do not conduct heat very well.

Convection • The transfer of heat

by the movement of fluids.

• In fluids (gases and liquids), molecules can move from place to place.

• As the molecules move, they take their heat along with them.

• Radiation, conduction, and convection work together to heat the troposphere.

• Air near Earth’s surface is warmed by radiation and conduction of heat from the surface to the air.

• Convection causes most of the heating of the troposphere