Cycling Energy

Energy does not cycle the way nutrients and atoms do. Energy enters the ecosystem from the Sun and exits after the organisms have taken as much as they need. Organisms release energy back into the biosphere as heat. Energy also enters the ecosystem from the interior of the Earth. It is usually in the form of heat, not the electromagnetic radiation from the Sun. There are finite amounts of carbon (C), nitrogen (N), and oxygen (O) on the planet. Those elements are recycled through the planet's resources. Energy is different in that it comes into the biosphere and then leaves.

Starting With The Sun

Our major source of energy is the Sun. Millions of miles away from Earth; our star has millions of nuclear reactions creating a large amount of energy. A small amount of that energy makes it to Earth. There are many different types of energy. We get visible light, heat, and ultraviolet radiation. Not all of it is good for the planet, but it all changes our world. The Earth absorbs only a small percent of the total energy hitting the planet.

The living organisms of the Earth generally use the heat (infrared radiation) and the visible light. The heat is good for everyone and lets our planet maintain a temperature where life can survive. The most important use of the visible light is to (1) see and (2) help plants run the process of photosynthesis. Photosynthesis is a process that happens when the energy from the Sun is used to power a chemical process that creates sugars and starches.

When Input Is Not Equal To Output

The amount of energy getting to the Earth is equal to the amount of energy leaving plus the amount used. Sometimes energy is trapped by the planet. There is a situation called a greenhouse effect that causes the energy of a planet to slowly increase over time. In the modern world we produce many compounds that float around in the atmosphere. If enough of these compounds were present, the infrared radiation reflected by the Earth could become trapped in the atmosphere and the temperature would slowly increase.

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