Each year, areas away from the Earth's equator experience an extended period of cooling temperatures and precipitation. In the Northern Hemisphere, this happens from September through February, while in the Southern Hemisphere, it occurs from around April to August. One of the biggest weather threats during the winter months of each hemisphere is the blizzard, a phenomenon accompanied by frigid temperatures, high winds and lots of snow. There are a number of types of blizzards, each uniquely different from the others.
A "traditional" blizzard is, for all intents and purposes, a snowstorm. This means that a blizzard will often include heavy snow and below-freezing temperatures. What makes a blizzard different than a snowstorm is that, unlike snowstorms, a blizzard must have high winds of at least 35mph, or 56 km/h. Additionally, a blizzard must reduce visibility to no more than 1,300 feet for extended periods of time.
Ground blizzards are different from traditional blizzards in that they do not dump any kind of significant snowfall. Instead a ground blizzard occurs when high winds blow snow that has already fallen. There are three main types of ground blizzards: horizontal advection, which has wind blowing horizontally across the Earth's surface, picking up snow and blowing it; vertical advection, in which there is an upward draft with the wind, blowing the snow high into the atmosphere to create waves hundreds of feet in height; and thermal-mechanical, which is essentially a combination of the previous two. While the latter is rare, it can bury a two-story house and be seen from space.
Lake-effect blizzards, seen most commonly along the shorelines of larger lakes such as the Great Lakes Region of North America, are the products of lake-effect snow combined with high winds. Lake-effect blizzards are relatively rare due to how lake-effect snow is formed. When cold winter winds blow across the warmer lake water, the winds lift the water vapor into the air and this is dumped along the shoreline. Because lake-effect snow doesn't often rise when the winds blow too fast, lake-effect blizzards are rare events.