The conversion of ice to water vapor is really a form of basic practical thermodynamics. Ice turns to water vapor naturally in stages, commonly as frost melts in the early morning, vaporizing. The process is thermal conversion from the frozen state to the natural state of water, and is directly related to the relative temperatures involved. This is also an atmospheric mechanism, in which atmospheric water at high altitudes forms ice crystals which are in turn converted to water vapor in a variety of forms. The amount of water vapor formed relates to temperature ratios.