has participant has quality has output water surface layer water-based rainfall freezing rainfall METAR:FZRA A surface temperature inversion is usually required. In such an inversion, the surface must have a temperature below freezing, while the temperature of the atmosphere where the precipitation forms is above freezing. Alternately, if the temperature of the ground surface and glazed objects is typically near or below freezing (0C or 32F), it is necessary that the water drops be supercooled before striking. Freezing rain can sometimes occur on surfaces exposed to the air (such as tree limbs) with air temperatures slightly above freezing in strong winds. Local evaporational cooling may result in freezing. Freezing rain frequently occurs, therefore, as a transient condition between the occurrence of rain and ice pellets (sleet). When encountered by an aircraft in flight, freezing rain can cause a dangerous accretion of clear icing. In aviation weather observations, this hydrometeor is encoded ZR by NOAA. Water-based rainfall which freezes either 1) on impact with a surface to form a coating of clear ice (glaze) or 2) after percolating through surface layers. decreased temperature frozen