A blizzard is a severe weather condition characterized by low temperatures
and strong winds (greater than 35 mph) bearing a great amount of snow,
either falling or blowing.
In order to be classified as a blizzard, as
opposed to merely a winter storm, the weather must meet several conditions.
The storm must decrease visibility to a quarter of a mile for 3 consecutive
hours, include snow or ice as precipitation,
and have wind speeds of at least 32mph (7 or more on the Beaufort Wind
According to Environment Canada a blizzard must have winds of 40 km/h or
more, have snow or blowing snow, visibility less than 1 km and a windchill
of less than -25 degrees celsius. All of these conditions must last for 4
hours or more.
When these conditions persist after snow has stopped falling, it is
called a ground blizzard.
An extreme form of blizzard is a whiteout,
where the downdrafts, coupled with
snowfall become so severe that it is impossible to distinguish the ground
from the air. People caught in a whiteout can quickly become
disoriented, losing their sense of up
and down as well as their sense of direction. Severe blizzards can also
occur in conjunction with arctic cyclones.
The word blizzard is a modern one of unknown origin; but it is
likely from the surname "Blizard." It was first widely used after the great
American winter storm now known as the "Blizzard of 1880." Certain types of
blizzards in the northeastern United States are colloquially known as
Nor'easters. Some believe the origin of the word "blizzard" is from it's
original use of scattered musket fire. An 1820 journalist was the first to
coin this word.