Blizzards | Blizzards Wiki | blizzards.net
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A blizzard is a severe snowstorm characterized by strong winds. By definition, the difference between blizzard and a snowstorm is the strength of the wind. To be a blizzard, a snow storm must have sustained winds or frequent gusts that are greater than or equal to 56 km/h (35 mph) with blowing or drifting snow which reduces visibility to 400 meters or ¼ mile or less and must last for a prolonged period of time — typically three hours or more. Snowfall amounts do not have to be significant. Ground blizzards require high winds to stir up already fallen snow.
Blizzards can bring near-whiteout conditions, and can paralyze regions for days at a time, particularly where snowfall is unusual or rare. The 1972 Iran blizzard, which caused approximately 4000 deaths, was the deadliest in recorded history.