1. Energy transferred from Earth's surface to the atmosphere through the evaporation and condensation processes.

2. If a change of state occurs from gas to liquid or liquid to solid, internal energy in the form of heat is released. If a change of state occurs from solid to liquid or liquid to gas, heat is required. Different compounds absorb and release different amounts of latent heat. Water takes nearly 600 kilocalories for each kilogram of water condensed.