Some heavy snowfalls turn a dull grey landscape into a beautiful winter wonderland, with clean, moist snow bending tree branches and children laughing as they fall into the soft snow. But, when biting winds blast the snow, beauty changes to danger. A blizzard is a severe snow storm with strong winds and low temperatures. A storm will be classified as a blizzard when the winds exceed 55 km/h, the temperature is well below normal, and visibility is reduced to less than 0.2 km. Most Canadians have witnessed blizzards and are aware of the many dangers they can bring.
Some blizzards develop in much the same way as thunderstorms, however, cold temperatures bring snow rather than rain and there is seldom any lightning. Some of the worst blizzards in Canada and the northern United States develop when a warm air mass, filled with moisture from the Gulf of Mexico and the Atlantic Ocean, moves northward and meets a cold Arctic air mass under a strong jet stream. The resulting mid-latitude storm, rotating counterclockwise, may drop up to a meter of snow in 24 hours. Another cause of blizzards is the combination of strong winds and the lake effect.
For example. In Ontario, prevailing winds often bring large snowfalls to regions east of Lake Huron and Georgian Bay. Lake-effect blizzards can last for days.
Blizzards usually have some devastating effects on transportation. They cause whiteout conditions on the highways, roads, and even on water, making driving very dangerous. Blizzards can close airports when it becomes too dangerous to fly. Public transportation usually comes to a stop. Bridges become icy and extremely dangerous in the winds. Emergency road crews have difficulty clearing the snow because more blows into the areas that have been just cleared. Many people become stranded when their vehicles get stranded in snow drifts.
Some blizzards develop in much the same way as thunderstorms, however, cold temperatures bring snow rather than rain and there is seldom any lightning. Some of the worst blizzards in Canada and the northern United States develop when a warm air mass, filled with moisture from the Gulf of Mexico and the Atlantic Ocean, moves northward and meets a cold Arctic air mass under a strong jet stream. The resulting mid-latitude storm, rotating counterclockwise, may drop up to a meter of snow in 24 hours. Another cause of blizzards is the combination of strong winds and the lake effect.
For example. In Ontario, prevailing winds often bring large snowfalls to regions east of Lake Huron and Georgian Bay. Lake-effect blizzards can last for days.
Blizzards usually have some devastating effects on transportation. They cause whiteout conditions on the highways, roads, and even on water, making driving very dangerous. Blizzards can close airports when it becomes too dangerous to fly. Public transportation usually comes to a stop. Bridges become icy and extremely dangerous in the winds. Emergency road crews have difficulty clearing the snow because more blows into the areas that have been just cleared. Many people become stranded when their vehicles get stranded in snow drifts.