Many chemical compounds in the atmosphere act as greenhouse gases. These gases allow sunlight (shortwave radiation) to freely pass through the Earth’s atmosphere and heat the land and oceans. The warmed Earth releases this heat in the form of infrared light (longwave radiation), invisible to human eyes. Some of the infrared light released by the Earth passes through the atmosphere back into space. However, greenhouse gases will not let all the infrared light pass through the atmosphere. They absorb some and radiate it back down to the Earth. This phenomenon, called the greenhouse effect, is naturally occurring and keeps the Earth’s surface warm. It is vital to our survival on Earth. Without the greenhouse effect, the Earth’s average surface temperature would be about 60° Fahrenheit colder, and our current way of life would be impossible.