Sleet-Green

Sleet Jack S. & Christina S.  Green Class Introduction Sleet is a form of precipitation that is made up of clear to translucent ice (6). For it to form, there needs to be specific conditions. It is often confused with freezing rain or hail, but it requires different conditions in order to form and it is structurally different as well. Sleet starts off as snow, then proceeds to melt when it encounters a warmer layer of the atmosphere (6). It differs from freezing rain in that it freezes before it makes contact with an object or the ground because of a larger cold layer over the ground. It is different from hail because it falls straight to the ground instead of traveling up and down due to strong updrafts in cumulonimbus clouds. Sleet is rare because of the very specific conditions it requires, but can be very dangerous when it does form. media type="youtube" key="SeG6UqyaCV0" width="425" height="350" Dangers Sleet can be a very dangerous form of precipitation, especially for people driving cars and other forms of transportation(5). It accumulates on the ground very quickly, sometimes even more efficiently than snow (1/5) but does not usually accumulate anywhere else because it bounces. Since it is a form of ice, it can be very slippery, making roads and sidewalks unsafe for people to use. Sleet can not do severe damage to crops or large transportation systems, unlike snow or freezing rain, because it is generally lighter and smaller which causes it to bounce on impact with hard surfaces (2). Since it does not usually accumulate above the ground, it usually does not knock out power lines or cause any severe, or permanent damage. to motorists. ||
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 * Sleet can accumulate quickly and become a danger

Conditions of Formation Sleet forming requires extremely rare conditions. For sleet to form, the air needs to be saturated, so the precipitation can form. In addition, there has to be a layer of freezing air, above a layer of air warmer than zero degrees celsius (6), which has to be above a layer of freezing air. For there to be air above zero degrees celsius, above freezing air, there needs to be inversion. Inversion is the phenomena of when rather then the temperature decreasing as the altitude increases, the temperature increases with altitude. It is usually caused when the sun goes down(4). This causes inversion because the ground then rapidly loses heat, also causing the air directly above it to lose heat. However, since air is a poor conductor of heat, the air that is higher above ground doesn't cool down, and becomes inverted(4). This is what causes the difference between snow and sleet, for when there is snow, it never begins to melt and refreeze. Snow is a form of sleet with more basic conditions. It is also different from hail, which is also essentially ice falling in the shape of pellets from the sky. The difference of the formation of hail is that it is caused by large updrafts. Updrafts are large gusts of wind, which carry the ice upwards; this causes the ice to gain more layers. Sleet does not require large updrafts, and tends to be much smaller then hail because it does not continuously gain more layers. The formation of sleet is also very similar to that of freezing rain, which also requires a layer of cold air above a layer of warm air above a layer of cold air, but is different in the fact that the snow needs to completely melt so it can supercool, for if it did not completely melt, the liquid particles would just freeze because they are in contact with a solid. Freezing rain needs a larger layer of warm air then sleet needs to form. Sleets very unique conditions cause it to be very rare(3). Thunder sleet One time, in Kentucky and Indiana, the true power and dangers of sleet were shown(3/7). On December 23rd and 24th in 2004(7), a sleet storm hit. During this storm, some areas received 15 to 16 inches of sleet(3). These mass amounts of sleet made transportation extremely difficult. This storm was also a not normal form of sleet. It was a form called "thunder sleet" where it was a thunderstorm with sleet rather then with rain(3). This sleet storm also broke records for amounts of snow and freezing rain falling. In addition, there was thick layers of ice coating many surfaces(7). This storm caused lots of damage to trees and roofs(7). This storm exemplified the precautions people should take to prevent damage from sleet and other forms of frozen precipitation. <span style="font-family: Georgia,serif; font-size: 24px;">Safety <span style="font-family: Georgia,serif; font-size: 14px;">Sleet is most dangerous for motorists or people traveling on foot. Once sleet accumulates to a certain amount, it becomes extremely dangerous to drive on(8). Experts say it is best to avoid it at all costs and to just stay inside. If one was to travel however, in a sleet storm, they should drive very slow and only take cars with snow tires or other reinforcements. If someone is planning on walking in sleet, it is important for them to wear boots with lots of traction to not slip. It would also be crucial to wear warm clothes as to not get a cold or some other form of sickness from being cold or wet. It is important to follow these before, during, and after a sleet storm safety tips in order to stay warm and out of danger (8).

Before a sleet storm:

-Make sure you have a disaster plan for a worst-case scenario.

-Prepare a disaster supplies kit for both your home and car. Include things such as flashlights, first aid kits, a change of clothes, blankets, water and canned food (8).

During a sleet storm:

It is important to stay indoors and also to dress warmly. You must eat and drink regularly, because food and drink provide the body with energy its needs for producing its own heat. If you need to go outside, be sure to wear layered clothing and gloves and a hat. If you are driving be sure to bring a cellphone and tell someone where you are going (8).

After a sleet storm:

Do not drive until the roads have been cleared and the storm has slowed down. Also be careful not to over-exert yourself while you shovel your driveway or clear sleet from other surfaces.

<span style="font-family: arial,helvetica,sans-serif; font-size: 110%; line-height: 19px;"> <span style="font-family: Georgia,serif; font-size: 24px;">Sources: (1)Emergency management agency. "Severe weather tips." //hamilton-co.gov//. EMA, n.d. Web. 17 Jan. 2012. <http://www.hamilton- co.org/ema/severe%20weather.htm>. Used for definitions, safety advice (2)Kcratv, and Ask-dirk. //Ask Dirk: What Is Sleet?// //youtube//. ask dirk, 2 Apr. 2009. Web. 17 Jan. 2012. <http://www.youtube.com/watch?v=SeG6UqyaCV0>. (3)National Geographic. "Sleet." //http://education.nationalgeographic.com///. National Geographic, n.d. Web. 17 Jan. 2012. <http://education.nationalgeographic.com/education/encyclopedia/sleet/kd/ ?ar_a=3&ar_r=3>. Used for slideshow, info on thunder sleet. (4)National Weather service. "What are temperature inversions?" //Noaa//. Noaa, n.d. Web. 17 Jan. 2012. <http://www.wrh.noaa.gov/slc/climate/TemperatureInversions.php>. Used for inversion (5)National Weather Sevice. "WINTER WEATHER PREPAREDNESS WEEK IN NORTH CAROLINA NOVEMBER 28 – DECEMBER 4, 2010." National Weather Service. Raleigh, North Carolina. Pdf file. (6)University of Illinois. "Sleet." //atmos.uiuc.edu//. University of Illinois, n.d. Web. 17 Jan. 2012. <http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/prcp/slt.rxm> (7)NOAA. "22 December 2004 central Kentucky and southern Indiana Historic Winter Storm." //crh.noaa.gov//. NOAA, n.d. Web. 17 Jan. 2012. <http://www.crh.noaa.gov/lmk/ ?n=22dec2004_winterstorm>. Used for info on thunder sleet  (8)Wtvy.com. "Safety in the Sleet." //Wtvy.com//. N.p., 9 Jan. 2011. Web. 15 Jan. 2012. <http://www.wtvy.com/home/headlines/113175099.html?storySection=story>.