Among the joys of the winter season, snow and its flakes are a source of wonder and fascination for most of us. Behind this fairytale spectacle are equally fascinating weather conditions. Snowfall, blizzards and snowstorms: these three winter weather phenomena captivate and baffle even weather experts.
Snowfall: how are snowflakes born?
Originally, the formation of clouds
Snowfall is the result of a complex process that begins with the formation of clouds. These are formed when moist air rises and cools. This weather phenomenon causes water vapour to condense and thus create small particles in the clouds. Depending on altitude and temperature, these particles are water droplets that can turn into ice crystals. This phenomenon of crystallization of water droplets is possible at high altitudes and when the temperature is low enough.
Snowfall occurs when the air temperature is low enough for water vapour to condense and form ice crystals.
The more ice crystals meet inside the cloud, the larger and more numerous they become. Then comes the phenomenon of aggregation where crystals come together and form larger snowflakes. When the latter are large and heavy enough, with the influence of gravity, they fall from the cloud to the ground and cause snowfall. Snowflakes can melt along the way if they pass through warmer layers of air, otherwise they fall to the ground to form a white carpet in which our tracks will remain marked.
The 5 Determining Factors
The phenomenon of snowfall depends on 5 very specific weather conditions:
These criteria allow experts to forecast weather conditions and estimate future snow amounts.
Blizzards: When the Wind Comes
A blizzard refers to a risky winter storm, when wind slabs cause reduced visibility. Blizzards form when there are low temperatures and strong winds laden with snowflakes. As with snowfall, several complex elements contribute to the formation of this phenomenon.
For blizzards, the temperature should be even lower than for simple snowfall. Above all, winds must be strong, at least 56 km/h (35 mph) over an extended period of time. These powerful winds blow away the snow that has already fallen, limiting visibility. Between falling snowflakes and blowing snow on the ground, vision can be almost white and make it difficult to make out anything from a few meters away.
Gusts of wind can also create snowdrifts, which are piles of snow along fences or in front of house fronts. Whether it's due to the lack of visibility or the snowbanks, travel becomes more difficult or even dangerous. To ensure people's safety, some blizzards require the closure of roads and airports. Thus, weather forecasts play a crucial role in anticipating, early warning of populations and management of emergency situations.
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Generally, blizzards are snowstorms that last for several hours. They occur in continental regions, away from the moderating influences of the oceans, when cold air masses from the Arctic meet warmer air masses.
Snowstorms: Nature Launches Its Frosty Carnival
This weather phenomenon is characterized by its sudden, localized onset and the amount of snow that has fallen. Snow can accumulate up to tens of centimetres or metres, leaving residents in a state of surprise.
The second characteristic that distinguishes snowstorms is that they last for several hours or days. Snow accumulates, with significant consequences for travel and daily activities.
Even though several weather phenomena can mix, snowstorms do not necessarily have very strong winds as in the case of blizzards. The biggest risk is the amount of snow that has fallen, which accumulates on the ground, houses, vehicles, etc. A major snowstorm can bury entire areas under huge snowdrifts.
The impact of these snowstorms depends on where they occur. Some regions are accustomed to and have the right equipment to prepare and quickly clear snow from the streets. On the other hand, a city that has never experienced this type of event can quickly find itself paralyzed by only a few centimeters of snow. If, on top of that, a blizzard comes, you can expect streets that are completely covered in snow and blocked, snow banks that accumulate up to the floors of houses or buildings or even power cuts.
Snowfalls, blizzards, snowstorms... Snow covers different realities, sometimes far removed from the pretty immaculate white coat of our childhood dreams.