Equivalent to heat of melting (Process in which two lighter atomic nuclei combine to form a heavier atomic nucleus. Very high temperatures are normally required in order for atomic nuclei to collide with sufficient energy to overcome the Coulomb barrier (their mutual electrostatic repulsions). Fusion that occurs under high-temperature conditions is called thermonuclear fusion. Fusion) and Heat absorbed or released as the result of a phase change. There are three basic types of latent heat each associated with a different pair of phases: fusion (solid-liquid), vaporization (liquid-gas), and sublimation (solid-gas). No temperature change occurs during a phase change, thus there is no change in the kinetic of a substance. It is the amount of heat that must be removed from one gram of a liquid at its freezing point to freeze it with no change in temperature.