A. Energy from the Sun • 1. Energy from the sun reaches the Earth through the process of radiation. • 2. Radiation is the transfer of energy. • 3. Not all of the sun’s energy reaches the Earth’s surface.
B. What happens to the sun’s energy when it reaches Earth? • 1. The Earth’s surface only receives and absorbs about 50% of incoming solar radiation. • 2. Reflection: Clouds and other particles in the atmosphere reflect about 25% of the sun’s radiation. • 3. Absorption: Gas and particles in the atmosphere absorb 20% of incoming radiation. • 4. Snow covered, icy or rocky surfaces also reflect about 5% of incoming radiation.
C. Thermal Energy Transfer • 1. Heat is thermal energy. • 2. Thermal energy transfer occurs through radiation, conduction and convection. • 3. All 3 of these occur in the atmosphere.
D. Radiation • 1. Radiation is the process that transfers energy from the sun. • 2. Example: heat coming from a heat source- The fire is radiating heat. • 3. Heat radiates from the Sun.
E. Conduction • 1. Conduction is the transfer of thermal energy by collisions between particles of matter. • 2. Example: Energy is transferred from a hot pot on the stove when you touch it. Direct Contact • 3. Conduction occurs where the atmosphere touches the Earth.
F. Convection • 1. Convection is the transfer of thermal energy by the movement of particles within matter. • 2. Example: boiling water circulates and steam rises. • 3. Remember convection currents- movement of molten rock in the mantle. Convection in the atmosphere, warm air rises, cools and sinks back down.
G. Circulating Air and Air Movement • 1. Energy is transferred through the atmosphere through convection. • 2. The differences in air temperature create a difference in air pressure. • 3. Warm air is less dense, cool air is more dense. • 4. Warm air rises and cool air sinks. Remember the convection lab. Hot magma rises to the surface, cools and sinks back down, over and over. • The movement and circulation of the air affects weather and climate around the world.