Diagram showing Earth's planetary energy balance. The arrows symbolize the balance between incoming radiation (yellow) and outgoing radiation (red) on Earth. Incoming heat energy is absorbed by Earth and warms the planet. Longer wave heat energy is then released back to space. However, some of this heat energy can be reflected back down again if it is trapped by clouds. This causes the greenhouse effect. Light energy may also not be absorbed by the Earth. Instead, it can be reflected by aerosols and emissions in the atmosphere.