The Sun
Most energy that humans use is a result of solar energy. Most of the the following ultimately derive from solar radiation:
When solar energy reaches Earth, 30% of it is immediately reflected back to space while the remaining 70% is absorbed by Earth in its oceans, atmosphere, and clouds. The 70% is then re-emitted as radiant heat (infrared radiation), but some of this energy is absorbed again and re-emitted by the lower atmosphere, which is what causes the greenhouse effect.
When Earth emits the same amount of energy as it absorbs, it balances the "energy budget," which in turn causes average temperatures to remain stable. However, the amount of energy that Earth absorbs is not the same in different times and places. For example, the tilt of our planet's axis in relation to its orbit provides predictable changes in the duration of exposure and amount of solar radiation that any specific point on Earth is exposed to. These predictable changes are the cause of our annual cycle of seasons and the predictable weather changes.
The sun's energy is not distributed evenly, with more energy hitting the areas towards the equator and less energy hitting the poles. This leads to temperature differences in the hydrosphere and atmosphere, which work to equalize by moving heat from areas with high amounts to areas with lower amounts. This heat transport is what causes ocean currents, atmospheric movement, evaporation, precipitation - weather in general that defines a specific climate.
Gradual changes in Earth's rotational and orbital patterns also change the intensity of solar radiation that our planet receives. At least for the past million years, changes have occurred in 100,000 year cycles that caused the ice ages and the warm periods in between them.
- food
- sources of electricity
- renewable energy (wind, hydroelectric, solar, etc.)
- hydrocarbons (oil, natural gas, etc.)
When solar energy reaches Earth, 30% of it is immediately reflected back to space while the remaining 70% is absorbed by Earth in its oceans, atmosphere, and clouds. The 70% is then re-emitted as radiant heat (infrared radiation), but some of this energy is absorbed again and re-emitted by the lower atmosphere, which is what causes the greenhouse effect.
When Earth emits the same amount of energy as it absorbs, it balances the "energy budget," which in turn causes average temperatures to remain stable. However, the amount of energy that Earth absorbs is not the same in different times and places. For example, the tilt of our planet's axis in relation to its orbit provides predictable changes in the duration of exposure and amount of solar radiation that any specific point on Earth is exposed to. These predictable changes are the cause of our annual cycle of seasons and the predictable weather changes.
The sun's energy is not distributed evenly, with more energy hitting the areas towards the equator and less energy hitting the poles. This leads to temperature differences in the hydrosphere and atmosphere, which work to equalize by moving heat from areas with high amounts to areas with lower amounts. This heat transport is what causes ocean currents, atmospheric movement, evaporation, precipitation - weather in general that defines a specific climate.
Gradual changes in Earth's rotational and orbital patterns also change the intensity of solar radiation that our planet receives. At least for the past million years, changes have occurred in 100,000 year cycles that caused the ice ages and the warm periods in between them.