Heat budget, also known as the energy budget or radiation budget, refers to the balance of incoming and outgoing energy flows in Earth’s atmosphere and surface. This balance is crucial for understanding and predicting climate patterns and changes.

Incoming solar radiation, or insolation, is the primary source of energy for Earth’s heat budget. This energy is largely absorbed by the Earth’s surface, heating it and driving atmospheric circulation and ocean currents. Some of the incoming solar radiation is also reflected into space by clouds, aerosols, and the Earth’s surface itself.

Once absorbed, the Earth re-emits this energy as longwave infrared radiation. Greenhouse gases, such as carbon dioxide and water vapor, trap some of this outgoing radiation in the atmosphere, thereby warming the planet in a natural process known as the greenhouse effect.

In Earth’s heat budget, approximately 70% of incoming solar radiation is absorbed by the atmosphere, land, and oceans, while 30% is reflected in space. For outgoing waves, about 70% of heat is radiated back into space, and 30% is absorbed by the atmosphere and clouds.

The heat budget varies across different regions and seasons due to factors like latitude, altitude, cloud cover, and surface characteristics (such as land or ocean). Imbalances in the heat budget can lead to changes in temperature, precipitation patterns, and weather events, influencing regional climates and global climate trends over time.