Precipitation

Precipitation is usually defined as all forms of hydrometeors, liquid or solid, which are free in the atmosphere and which reach the ground. In this report the definition is extended to those hydrometeors which do not reach the ground, but impinge on a flying surface, such as space vehicles. Accumulation is reported in depth over a horizontal surface; i.e., millimeters or inches for the liquid phase and in depth or equivalent depth of water equivalent for the frozen phase.