If greenhouse gas molecules were enlarged, this would be their general shape.
NCAR

The Greenhouse Effect

Have you ever been inside a greenhouse on a cold winter day? It might be cold outside, but inside the greenhouse green plants grow well in the warmth and sunshine. Greenhouses are made of glass and are designed to trap energy inside. The atmospheres of some planets are able to trap energy too. Energy from the Sun can enter the atmosphere, but not all of it can easily find its way out again.

What blocks the Sun’s energy from escaping a planet’s atmosphere? Molecules in the atmosphere called greenhouse gases absorb the heat.

Without greenhouse gases, the surface of the Earth would be as cold as the surface of Mars. But too many greenhouse gases can cause the temperature to increase out of control. That’s why it’s so warm on Venus.

Earth's greenhouse effect is growing stronger because there are more greenhouse gases in the air. More greenhouse gases are added to the air when fossil fuels are burned. This is causing Earth's climate to warm.

Last modified February 1, 2010 by Lisa Gardiner.

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