The Earth’s surface, warmed by the Sun, releases heat into the atmosphere. Some heat is absorbed by greenhouse gases like carbon dioxide and then released to space (A). Some heat goes straight out to space (B). Some heat is absorbed by greenhouse gases and then bounced back to Earth (C). More carbon dioxide in the atmosphere means that more heat will be stopped by greenhouse gases, warming the planet.
Click on image for full size
Lisa Gardiner / Windows to the Universe
Earth's Greenhouse Effect
Not all of the energy from the Sun that arrives at Earth can leave easily. After being transformed into heat, it can become trapped by certain gases in the air. This is a natural process called the greenhouse effect. Without any greenhouse effect, Earth’s temperature would be below freezing. However, Earth’s greenhouse effect is getting stronger because we are adding more greenhouse gases to the atmosphere. This is causing global warming.
Sunlight warms the Earth’s surface and than the surface warms the air above it. Some of this heat makes its way back to space. But along the way a lot of it is absorbed by greenhouse gases in the atmosphere. They radiate the heat back to the Earth's surface, to another greenhouse gas molecule, or out to space.
The amounts of greenhouse gases are increasing as fossil fuels are burned, which releases greenhouse gases. Greenhouse gases also make their way to the atmosphere from other sources. Farm animals, for example, release methane gas as they digest food. As cement is made, it releases carbon dioxide.
With more greenhouse gases, heat on its way out of the atmosphere is more likely to be stopped. The added greenhouse gases catch the heat and then send it off in a new direction. Some of the heat will head away from the Earth, some of it will be caught by another greenhouse gas molecule, and some of it will wind up back at the Earth’s surface again. With more greenhouse gases, heat will stick around, warming the planet.
Shop Windows to the Universe Science Store!
The Summer 2010 issue of The Earth Scientist
, available in our online store
, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
You might also be interested in:
Methane is a kind of gas. There is a small amount of methane in the air you breathe. A methane molecule has carbon and hydrogen atoms in it. Methane is a greenhouse gas. That means it helps make Earth...more
Carbon dioxide (CO2) is a kind of gas. There isn't that much carbon dioxide in Earth's atmosphere, but it is still very important. Carbon dioxide is a greenhouse gas. That means it helps trap heat coming...more
Only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases. But they have a huge effect on climate. There are several different types of greenhouse gases, but they all have something in...more
The Sun Climate can change if there is a change in the amount of solar energy that gets to Earth. A change in the solar cycle can impact climate. The effect is too small to be the reason that global warming...more
There are many different ways that the plants, animals, and other living things affect climate. Some produce greenhouses gases that trap heat and aid global warming through the greenhouse effect. Others...more
Carbon moves around the Earth through the carbon cycle. It can move between the atmosphere, the water, living things, and even rocks. Today, the carbon cycle is changing. More carbon is moving into the...more
Scientists are sending tiny airplanes buzzing in the sky to find out how air pollution can impact weather, climate, and global warming. The tiny airplanes look like regular planes but they have only a...more