The rate of solar energy striking Earth averages 168 watts per square meter. The rate of energy radiated from Earth's surface averages 390 watts per square meter. Comparing these numbers, one might expect that the planet would cool quickly, yet it does not. Why not?

Earth receives energy from the Sun in the form of solar radiation. This energy is absorbed, reflected, and reradiated by the Earth's surface, its atmosphere, and its oceans. To maintain a stable temperature, Earth must balance the incoming solar energy with the energy it radiates back into space.

The greenhouse effect is a natural process that helps maintain Earth's temperature by trapping some of the outgoing infrared radiation and sending it back to the surface. Greenhouse gases like water vapor, carbon dioxide, and methane in the atmosphere absorb and re-emit the infrared radiation, preventing a portion of it from escaping into space. This ultimately leads to a warmer Earth.

The incoming solar energy to Earth (168 W/m^2) is not equal to the outgoing energy (390 W/m^2). But when considering the greenhouse effect, some of the radiated energy is trapped and returns to Earth's surface rather than directly escaping. This leads to a balance between the incoming and outgoing energy, keeping Earth's temperature stable instead of cooling down.

Several factors affect Earth's energy balance: 1. Albedo: The reflectivity of Earth's surface and atmosphere (clouds, ice caps, etc.) influences how much solar energy is absorbed and radiated back into space. A higher albedo means less energy is absorbed, resulting in cooler temperatures. 2. Greenhouse Gas Concentration: The balance between incoming and outgoing energy is affected by the amount of greenhouse gases in the atmosphere. Higher concentrations of these gases trap more outgoing radiation, leading to an increase in Earth's temperature. 3. Cloud Cover: Clouds can both reflect incoming solar radiation back into space and trap outgoing radiation, making their overall impact on the energy balance complex and dependent on factors like cloud type and altitude.

Comparing the incoming and outgoing energy rates on Earth might give the impression that the planet should cool down quickly; however, this does not account for the greenhouse effect. The greenhouse gases in the atmosphere trap some of the outgoing infrared radiation and send it back to the surface, maintaining a stable temperature on Earth. Factors like albedo, greenhouse gas concentration, and cloud cover also play essential roles in the overall energy balance, ensuring that the Earth does not cool down as quickly as it might seem.