When the air temperature at ground level falls below the freezing point of water, which is 32°F (0°C), it means much of the water on the surface will turn to ice, with often spectacular and dangerous results. Freezes, blizzards and a build up of snow that may lead to avalanches can form and all of these have produced great loss of life and infrastructure damage throughout history.
A freeze can produce a magnificent glass- like panorama across the countryside, but its beauty masks a whole raft of dangers and problems. Freezes are generated when rain falls from a layer of air that is warmer than 32° f (0°C) into a layer of air close to the ground that has a temperature below freezing. This can produce sleet, which consists of pellets of solid ice or a kernel of water surrounded by a coating of ice.
A much more dangerous situation occurs when the cold layer near the ground is only just below freezing or is quite shallow. In this instance, it`s possible for the rain to reach the surface in liquid form and then freeze immediately, forming a layer of ice over all outdoor surfaces. When this type of situation continues for several hours, the ice accumulation can become considerable. Sometimes, the term “ice storm” is used to describe freezes.
These large accumulations of ice are potentially dangerous for people on footpaths and roadways. Pedestrians can easily fall and break limbs and there is also an immediate jump in motor vehicle accidents as slippery conditions create mayhem on the roads. As a result, there is dramatically increased pressure on ambulance services and hospital infrastructure.
Power and communications systems carried by overhead wires are particularly vulnerable to ice storms, as the ice accumulation can become heavy enough to snap the wires, or bring down trees that fall across them. This can seriously affect telephone and internet connections, cable television and all household electricity supplies, including of course, electrically powered heating devices.
Freezes or ice storms are a serious issue for areas of the Northern United States, Canada, Northern Europe, Russia and parts of Northern China.
Another possible consequence of a big freeze is the much- feared avalanche. This is an accumulation of snow that has become detached from its area of origin, after which it slides downhill under the influence of gravity. It can be a localized phenomenon, involving only a small volume of snow moving a short distance or it can involve huge masses of snow and ice moving at tremendous speed for several miles, turning into a destructive battering ram that flattens villages and buries the inhabitants. Historically, avalanches have caused substantial loss of life and property damage, so they are regarded as a real hazard in alpine areas all over the world, with the European Alps, in particular, considered a major danger zone.
The Hazards of Blizzards
The blizzard is another major hazard of the big freeze environment. This is a storm that contains strong winds and heavy snowfall, along with very cold temperatures. The combination of these elements creates blowing snow, with near- zero visibility, deep snowdrifts and potentially lethal wind- chill temperatures. A blizzard normally occurs at very low temperatures and is worse when the existing snow cover consists of fine, light snow that is called “powder”.
The severity of a big freeze is often measured through the “wind chill” factor, which is a combination of temperature and wind speed. Wind carries heat away from the human body and produces a wind chill temperature that is less than the actual temperature.
What to do in a Big Freeze:-
Monitor all weather warnings that are transmitted through the media, including radio, television, newspapers and the internet.
If in an avalanche area, don`t attempt to hike or drive without checking to see if warnings have been issued.
Stay inside during and immediately after an ice storm. Both walking and driving will be quite dangerous.
Stay inside if a blizzard is expected and prepare for a long wait. Make sure you have food and warm clothes available. Be prepared for power outages and have alternative heating and lighting ready for use.
If caught in a motor vehicle in a blizzard, stay inside. Run the engine for around 10 minutes each hour with the heater on, but leave the window down a little for ventilation.
If caught outside in a blizzard, prepare a windbreak or snow cave for shelter. It`s most important to get out of the wind and if possible, start a fire for warmth.