A blizzard is a severe weather condition characterized by low temperatures and strong winds, greater than 35 miles per hour, bearing a great amount of snow.
    Because the factors for classifying winter storms are complex, there are many definitions of what a blizzard truly is. But it is generally agreed that 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 three hours running, include snow or ice as precipitation(冰雹), and have wind speeds of at least 32 miles per hour, which means force seven or more on the wind scale.
    Another standard, according to Environment Canada is that the winter storm must have winds of 40 kilometers per hour or more, plenty of snow, visibility less than one kilometer, a temperature of less than minus 25 degrees Celsius, and all of these conditions must last for four hours or more, before the storm can properly be called a blizzard.
    When all of these conditions continue after snow has stopped falling, the storm is referred to as a ground blizzard. An extreme form of blizzard is a whiteout, when the downdrafts, together 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 along with arctic cyclones.