Earth’s Energy Budget

Modes of Energy Travel Heat Energy can be transferred in three specific ways: Heat Energy can be transferred in three specific ways: Conduction Conduction Convection Convection Radiation Radiation

Heat Transfer Conduction - transfer of energy from atoms that collide with other atoms (occurs in earth materials and metals) Conduction - transfer of energy from atoms that collide with other atoms (occurs in earth materials and metals) Convection – atoms in a gas or liquid transfer heat by moving vertically in a space (a convection oven) Convection – atoms in a gas or liquid transfer heat by moving vertically in a space (a convection oven) Radiation – transfer of energy through waves. This is how sunlight gets to earth. Radiation – transfer of energy through waves. This is how sunlight gets to earth.

Solar Energy When radiant solar energy reaches the Earth, 2 different interactions occur: When radiant solar energy reaches the Earth, 2 different interactions occur: Reflection – the radiation is reflected back into space unchanged Reflection – the radiation is reflected back into space unchanged Absorption – the radiation is absorbed by the atmosphere of the Earth’s surface. Absorption – the radiation is absorbed by the atmosphere of the Earth’s surface. 70% absorbed 70% absorbed 30% reflected 30% reflected

Breakdown

Earth’s “Constant” Temperature The Earth retains a relatively constant temperature. The Earth retains a relatively constant temperature. To do this, it must lose as much energy back to space as it absorbs from the Sun. To do this, it must lose as much energy back to space as it absorbs from the Sun.

Energy and Water Most of the sun’s energy hits water on earth (earth is 70% water) Most of the sun’s energy hits water on earth (earth is 70% water) Interactions between the sun’s energy and water have a major influence on weather but it depends on what state the water is in Interactions between the sun’s energy and water have a major influence on weather but it depends on what state the water is in White snow reflects up to 90% of the incoming solar energy White snow reflects up to 90% of the incoming solar energy Ice reflects about 50% Ice reflects about 50%

Energy and Water Liquid water reflects only about 7% (i.e. it absorbs about 93%!!!) Liquid water reflects only about 7% (i.e. it absorbs about 93%!!!) Therefore many weather systems are initiated from the energy that is absorbed by the oceans Therefore many weather systems are initiated from the energy that is absorbed by the oceans

Water in the Air Water exists in the air as a gas (water vapour) Water exists in the air as a gas (water vapour) When the air becomes saturated, condensation of the water vapour occurs (forms liquid water droplets) When the air becomes saturated, condensation of the water vapour occurs (forms liquid water droplets) The amount of water vapour in the air is measured by humidity The amount of water vapour in the air is measured by humidity

The Water Cycle The incoming sun causes ~23% of liquid water to evaporate The incoming sun causes ~23% of liquid water to evaporate Evaporation occurs from all bodies of water but mostly the oceans Evaporation occurs from all bodies of water but mostly the oceans Evaporation occurs from plants through their leaves through a process called transpiration (or evapotranspiration) Evaporation occurs from plants through their leaves through a process called transpiration (or evapotranspiration)