February 2007 North American blizzard Due to the three-dimensional nature of the atmosphere, warm air was poised to overtake the cold air closer to the ground, causing precipitation to melt, then refreeze as either sleet or freezing rain. As temperatures hovered around freezing on the southern edge of the storm track, light snow accompanied freezing rain and sleet. The freezing rain coated all surfaces with thick layers of ice, including power lines and tree limbs which break under the additional weight. Some locations in the Mid-Atlantic received several inches of sleet. Four inches (100 mm) of sleet caused travel difficulties and hampered cleanup efforts in
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