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