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Types of Precipitation Precipitation forms when a portion of the atmosphere becomes saturated with water vapor and water condenses. Air becomes saturated by either the cooling of the air to the dew point, which can be achieved through a diabatic cooling, conductive cooling, radiational cooling, and evaporative cooling or by adding moisture to the air.

Reference;Winter Precip.jpg (133341 bytes) []. Accessed on 11/16/10 Rain   References: Raindrops/Best Funny Gift and Animated Pics updated Daily-Gift Bin []. Accessed 11/16 /10 Rain is one of the four types of precipitation that appear as liquid water. Rain consists of water droplets in the atmosphere that fall to the ground. One of the reason rain occurs is because the raindrops are formed in the clouds as liquid water and fall to the ground through the collision process which means that little droplets of water combine and grow large enough till they fall to the earth. When the water droplets are 0.2mm, they are called mist and once they are 0.5 mm large they are already raindrops ready to fall to the ground. Therefore, rain usually falls to the ground when the water droplets are between 5 to 8 mm. Furthermore rain also happens because the temperature is above the freezing point and for this reason ice particles melt and fall to the earth as rain.

The following video can help to understand the process of precipitation as solid water . media type="youtube" key="Yw275056JtA?fs=1" height="181" width="349" Source: The water Cycle by David Bydlowski, ScienceExplotion.com . [] Accessed 11/1510



Hail

Hail occurs as a result of strong updrafts in thunderstorms, however rarely when surface temperature is below freezing. Water drops will rise in a circular motion to the top of cumulonimbus clouds where the temperature is below freezing. These drops will freeze into a hailstone. The updrafts will cause the hailstone to rise, and then gravity will cause it to fall; creating a cycle for the hailstone. Each cycle that the hailstone completes causes it to grow in size, eventually becoming to large for the updrafts to keep it up and it falls to the ground. Typically the stronger the thunderstorm the larger the hailstone will grow to be, because the updrafts of the cloud will be greater causing the hailstone to be suspended longer in the air. Reference: Precipitation Types, angelfire.com  []       Reference: Hail Damage, rapiddent.com   http://www.rapiddent.com.au/images/HailFormation.jpg    __ Harmful effects of hail: __ Source: Damage Caused by Hail, allaboutweather.org http://allaboutweather.org/wp-content/uploads/2010/07/hail-damage.jpg                 Freezing Rain  Freezing rain occurs when there is a layer of air that is "warm" above a layer of air that is below freezing right above the Earth's surface. The precipitation first falls as snow and as it falls through the warmer air layer the snow melts. The water drops become super-cooled as they fall through the freezing air which causes the rain to freeze on contact when it hits the surfaces. __Harmful effects of freezing rain:__
 * Damage is most notably done to:
 * automobiles, by denting them and shattering windshields.
 * aircraft, by causing problems on runways and also damaging planes in flight; sometimes causing severe damage within seconds
 * livestock, by injuring animals
 * crops, the crops that are most subject to damage are
 * corn
 * tobacco
 * wheat
 * soybeans
 * roofs, certain roofs such as tin hold up better to hail storms, mainly suffering cosmetic damage. However other roofs may develop cracks.
 * Hail stones have also been reported for having caused concussions and fatal head traumas.
 * power outages. When freezing rain falls on power lines, the weight of the the ice causes support poles, insulators, and lines to break.
 * black ice or glaze. Ice that accumulates on the roads makes driving dangerous because there is little to no traction vehicles need to drive safely.
 * plant and crop destruction. When ice freezes on plants, they cannot take the weight of the ice causing them to die or get crushed. Even trees suffer damage from freezing rain because the branches will break off of the trees due to the weight of the ice on them.
 * Planes and aircraft are effect by freezing rain. When ice freezes onto airplanes the change in weight and shape of airfoils will reduce lift and increase drag. Extreme structural ice even poses a problem for aircraft with the most advanced deicing equipment as a slight change in weight effects how well an airplane can stay aloft.

Sleet Sleet is frozen raindrops. It falls as snow first but as it falls through the atmosphere, the precipitation goes through a warm layer of air. The snow melts and falls as rain. But before it hits the ground, it goes through a layer of air that is below freezing and the raindrops freeze again hitting the surface as frozen raindrops. __Harmful effects of sleet:__
 * Like freezing rain, sleet makes the roads extremely slippery making driving conditions dangerous. Sleet, however, is more visible than freezing rain on roads because sleet are frozen raindrops.
 * Plants can die when there is sleet on the ground because of the cold temperatures.

Snow Snow forms due to the condensation of water vapor on a very small ice crystal or dust particle in the atmosphere at temperatures below freezing. The Bergeron-Wegener process occurs during which water vapor does a direct state change to ice when the temperature reaches the dew point. This deposition results in the formation of ice crystals usually hexagonal in shape. As more water vapor is brought to the cloud by updrafts, the ice crystals grow larger by the same process, eventually to the point that these crystals fall towards the ground in the shape of snowflakes. Unlike the other forms of precipitation, snow stays below freezing throughout it's entire descent through the atmosphere. However, snow forms in open structures meaning it is soft to the touch unless it is packed by external pressure.

media type="custom" key="7575983" __ Harmful Effects of Snow __
 * Avalanches
 * Blizzards
 * Snow Blindness
 * Disrupt means of transportation
 * Black Ice

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