Blizzard
Posted on 23. Apr, 2010 by thanate in Blizzards
A blizzard is a severe storm condition characterized by low temperatures, strong winds, and heavy snow. Many blizzards are in the Canadian region. By definition, the difference between blizzard and a snowstorm is the strength of the wind. Ground blizzards are a variation on the traditional blizzard, in that ground blizzards require high winds to stir up snow that has already fallen, rather than fresh snowfall.
Photo: potterysue
Regardless of the variety of blizzard, they can bring near-whiteout conditions, which restrict visibility to near zero. Blizzards have a negative impact on local economies and for days at a time can paralyze regions where snowfall is unusual or rare.
According to Environment Canada, a winter storm must have winds of 40 km/h or more, have snow or blowing snow, visibility less than 500 feet, a wind chill of less than ?25 °C, and all of these conditions must last for 3 hours or more before the storm can be properly called a blizzard.
Many European countries, such as the UK, have a lower threshold: the Met Office defines a blizzard as “moderate or heavy snow” combined with a mean wind speed of 30 mph and visibility below 650 feet.
Meteorologists refer to blizzard-like conditions with no snow falling as a ground blizzard, because all the snow is already present at the surface of the earth and is simply being blown by high winds. Ground blizzards require large expanses of open and relatively flat land with a sufficient amount of accumulated and loosely packed, powdery snow to be blown around
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