Vaporization (or vaporisation in British English) of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization: evaporation and boiling. Evaporation is a surface phenomenon, whereas boiling is a bulk phenomenon.
Evaporation is a phase transition from the liquid phase to vapor (a state of the substance below the critical temperature) that occurs at temperatures below the boiling temperature at a given pressure. Evaporation occurs at the surface. Evaporation occurs only when the partial vapor pressure of a substance is less than the equilibrium vapor pressure. For example, due to steadily decreasing pressures, vapor pumped out of a solution will eventually leave behind a cryogenic liquid.
Boiling is also a phase transition from the liquid phase to the gas phase, but boiling is the formation of vapor as vapor bubbles below the surface of the liquid. Boiling occurs when the equilibrium vapor pressure of the substance is greater than or equal to the ambient pressure. The temperature at which boiling occurs is the boiling temperature, or boiling point. The boiling point varies with ambient pressure.
Sublimation is a direct phase transition from the solid phase to the gas phase, skipping the intermediate liquid phase. Because it does not involve the liquid phase, it is not a form of vaporization.
The term vaporization has also been used colloquially to refer to the physical destruction of an object that is exposed to intense heat or explosive force, where the object is actually blown into small pieces rather than literally converted to gaseous form. Examples of this usage include the “vaporization” of the uninhabited Marshall Island of Elugelab in the 1952 Ivy Mike thermonuclear test.
Upon impact of a large enough meteor or comet, detonation of a bolide, nuclear fission, thermonuclear fusion, or detonation of a theoretical antimatter weapon, a stream of so many photons of gamma rays, X-rays, ultraviolet, visual light, and heat hits matter in such a short time (a large number of high-energy photons, many of which overlap in the same physical space) that all molecules lose their atomic bonds and “fly away”.
All the atoms lose their electron shells and become positively charged ions, in turn emitting photons of a slightly lower energy than they had absorbed. All of this matter becomes a gas of nuclei and electrons that rise into the air due to the extremely high temperature or bind together as they cool. Matter vaporized in this way is immediately a plasma in a state of maximum entropy and this state is steadily reduced through the factor of time passing due to natural processes in the biosphere and the effects of physics at normal temperatures and pressures.
A similar process occurs during ultrashort pulse laser ablation, where the high flux of incoming electromagnetic radiation strips the surface of the target material of electrons, leaving positively charged atoms that undergo a coulombic explosion.