Precipitation types the preceding adjective "freezing", becoming known as freezing rain or freezing drizzle. Frozen forms of precipitation include snow, ice needles, sleet, hail, and graupel. Their respective intensities are classified either by rate of fall, or by visibility restriction. Precipitation falls in many forms, or phases. They can be subdivided into: The parenthesized letters are the METAR codes for each phenomenon. Precipitation occurs when local air becomes saturated with water vapor, and can no longer maintain the level of water vapor in gaseous form. This occurs when less dense moist air cools, usually when an airmass rises through the atmosphere. However,
Cumulonimbus and aviation the shear between rising and sinking air. If the airspeed is too high at this point, the airplane will break apart. The crash of Flight AF 447 is indirectly related to this situation: the pilot, being short on fuel, opted for the shortest path while crossing the thunderstorm line associated with the intertropical convergence zone, and the pitot tubes iced over. What followed is known. On-board radars can be deceiving. Hail shafts generate weak radar echoes and are significantly more dangerous than cloudbursts. Close to the ground, heavy rain (or snow at altitude) tends to dampen turbulence (it is said