SleetPurple

// Sleet //
Matt C. and Nobska Purple Class Introduction Sleet is frozen raindrops that hit the surface of the earth as ice pellets.(1)Sleet is easily visible, and causes surfaces to become very slick. (3)

Dangers Sleet can be very dangerous; it is a component of an ice storm, which is extremely destructive. The ice coats tree limbs and power lines, which can sag and break. This causes widespread power outages, and structure damage. People can be injured by falling tree branches, and the treacherous ice can cause falls and other serious accidents. (1)



Conditions of Formation Sleet progresses ahead of a warm front, and its difficult to forecast because it develops under specialized atmospheric conditions. Partially melted snowflakes become sleet at an average temperature of 32 degrees F (below 0 degrees C). It forms when rain passes through a cold layer of air and freezes. The rain is transformed into ice pellets. Sleet occurs in the winter only, when warm air is forced over a layer of cold air. (2) This is different from hail which is a similar form of precipitation. The difference is that hail is formed differently from sleet and that hail can come in any season while sleet occurs strictly in the summer. (4)It is an indicator of both cold and warm air aloft in a winter storm system. (1) Areas of sleet are usually located on the colder side (most often north) of a freezing rain band ahead of a warm front, at a low air pressure center. (3) Precipitation cannot originate as sleet. Sleet must be formed by first starting as either rain or snow, then when the precipitation falls, it must pass through a barrier of air that is either above or below freezing (depending on what the precipitation started as) to become sleet.

Historical Examples In early December of 2008, a large ice storm including sleet, hail and freezing rain hit New England. The storm caused problems of fallen tree branches which blocked roads and fell onto cars and houses. Millions of homes and buisness' were without power for weeks at a time. They was no one reported killed because of the storm; but a man who hooked up a generator in his home without power during the storm died in New Hampshire of carbon monozide poisoning. (6)

=Safety = In an ice storm or when sleet occurs, it is safest to stay inside to avoid personal injury. Keeping emergency supplies available for possible power outages is also a good idea. (1) Sleet is not particularly dangerous, but it can cause injuries by slipping and falling on the ice. Sources