Latent Heat is the energy required to change a substance to a higher state of matter (solid > liquid > gas) or consequently, ice, liquid water and water vapour. This same energy is released from the substance when the change of state is reversed (gas > liquid > solid).
Latent heat of condensation (or fusion) is the amount of heat energy release to the environment when a gas changes its state to a liquid. For one gram of water, the amount of heat energy released is 540 calories at a temperature of 100 degrees Celsius. Latent heat of sublimation (solid ice to water vapor) is even greater.
Latent heat of vaporization is the amount of heat energy required from the environment to change the state of a liquid to a gas. For one gram of water, the amount of heat energy required is 540 calories at a temperature of 100 degrees Celsius.
Latent heat flux is the global movement of latent heat energy through circulations of air and water. Atmospheric circulation moves latent heat energy vertically and horizontally to cooler locations where it is condensed as rain or is deposited as snow releasing the heat energy stored within it. Large quantities of radiation energy are transferred into the Earth's tropical oceans. Radiant energy enters these water bodies at the surface when absorbed radiation is converted into heat energy. The warmed surface water is then transferred downward into the water column by conduction and convection. Horizontal transfer of this heat energy from the equator to the poles is accomplished by ocean currents.