SleetBlue

= Sleet Emily M. and Gwen W. = Blue Class

=Introduction = Sleet is made of a combination of frozen rain and melted snow.(3) Sleet is different from most other types of weather because it is seen exclusively in the winter months.(3) When sleet falls, the temperatures in the sky are usually just above freezing point, and as the sleet passes between the different layers of the sky the sleet goes through physical changes, but finally falls to the ground as sleet.(4) This type of precipitation can coat trees or streets with a thin layer of ice. To see diagrams of the layers of sleet, go to http://ww2010.atmos.uiuc.edu/(Gl)/guides/mtr/cld/prcp/slt.rxml.  A diagram of the sky and sleets journey.

=Definition = Sleet is precipitation in the form of ice pellets created by the freezing of rain as it falls. (6) Dangers The dangers of sleet include the risk of people falling or slipping easily on the icy coating it leaves, and cars skidding along causing accidents (1). Places that do not often see winter weather are most at risk because people may not know how to handle the situation or not have the right equipment. Another danger is the icy layer can cover power lines, weighing it down and sometimes causing them to break resulting in power outages (2). An example of the size of sleet is shown in this video, in Pennsylvania in 2008. http://www.youtube.com/watch?v=AOBJKwJ_-m4&feature=related  An example of the icy sheet that sleet can leave. Conditions of Formation The conditions under which sleet forms are usually those assosiated with a winter storm. Especially in the south, cold air mass is followed by precipitation a few days later. When the two arrive at the same time sleet (or in some cases hail) is formed. When precipitation passes through different layers of cold and warm air, it freezes (when temperature is below freezing), melts, and then refreezes (2). To see an example of the formation of sleet, go to http://www.geography.hunter.cuny.edu/~tbw/wc.notes/5.cond.precip/sleet_formation.htm.  Sleet drops can get to be huge, in this example about the size of marbles.

Historical Examples In January of 1961, a huge sleet storm passed through North Carolina. Practically the entire state was covered with ice in the early morning. Not only were there numerous accidents as a result of this storm, but a person was killed as well. Power lines were out for periods of multiple hours and schools over half of the state were closed. Another effect was fires caused by overheated heating systems.(5)This shows how sleet can leave the roads icy and dangerous for travel. Sleet can cause layers of ice to freeze on trees.

Safety In order to keep safe from sleet, it is best to stay inside following the downfall. The ice resulting from the storm can be dangerous and can cause more accidents. It is best to keep spare supplies in the event that the power lines go out.(2)

Sleet can cause a thin layer of ice on pavement.

Sources 1. Fact Monster. "Sleet" Columbia Electronic Encyclopedia. 2002  2. Wise Geek. "What is sleet?" Copyright Conjecture Corporation. 2003- 2010  3. Reference Answers. "Sleet: Definition" Answers Corporation. 2010  4. Smithsonian Astrophysical. "Satellite Measurement of the Effects of Rain and Sleet" NASA/ Smithsonian. 2000  5. North Carolina State University. "Winter Weather" State Climate Office of North Carolina. 2010. 