Heat stored in a medium during a change of its state that does not change its temperature.
The concept of latent heat can be explained by using a pot of water as an example. If the pot is put on a stove the temperature of the water rises until the water boils. If the water is kept on the stove the water will continue to boil but no longer increase its temperature, which shows that no more heat is added to the liquid. All heat then goes into the process of vaporization and is carried away by the evaporating water molecules.
Latent heat plays an important role in the Earth's climate as a transport mechanism for energy. When water evaporates from the ocean, the land or plants, the heat required for the process is extracted from ocean, land and plants and transferred to the atmosphere. The water molecules, and with them the latent heat, are then carried by the winds over large distances. The latent heat is released when condensation occurs and the water rains out from the atmosphere, causing a heating of the atmosphere. This is a very efficient way of moving excess heat from the tropics to colder regions.