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A blizzard is a severe snowstorm characterized by strong sustained winds of at least and lasting for a prolonged period of time—typically three hours or more. A ''ground blizzard'' is a weather condition where snow is not falling but loose snow on the ground is lifted and blown by strong winds. ==Definition== In the United States, the National Weather Service defines a blizzard as a severe snowstorm characterized by strong winds causing blowing snow that results in low visibilities. The difference between a blizzard and a snowstorm is the strength of the wind, not the amount of snow. To be a blizzard, a snow storm must have sustained winds or frequent gusts that are greater than or equal to with blowing or drifting snow which reduces visibility to or less and must last for a prolonged period of time—typically three hours or more.〔(Blizzards )〕 While severe cold and large amounts of drifting snow may accompany blizzards, they are not required. Blizzards can bring whiteout conditions, and can paralyze regions for days at a time, particularly where snowfall is unusual or rare. A severe blizzard has winds over , near zero visibility, and temperatures of or lower.〔("Blizzard" ) ''Encyclopædia Britannica Online'' retrieved 17 March 2012〕 In Antarctica, blizzards are associated with winds spilling over the edge of the ice plateau at an average velocity of .〔 Ground blizzard refers to a weather condition where loose snow or ice on the ground is lifted and blown by strong winds. The primary difference between a ground blizzard as opposed to a regular blizzard is that in a ground blizzard no precipitation is produced at the time, but rather all the precipitation is already present in the form of snow or ice at the surface. The Australia Bureau of Meteorology describes a blizzard as, "Violent and very cold wind which is laden with snow, some part, at least, of which has been raised from snow covered ground." Blizzard conditions of cold temperatures and strong winds can cause wind chill values that can result in hypothermia or frostbite. The wind chill factor is the amount of cooling the human body feels due to the combination of wind and temperature. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「blizzard」の詳細全文を読む スポンサード リンク
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