Cold waves
A cold wave, sometimes known as a cold snap, is a weather event involving a cooling of the air, or the invasion of very cold air, over a large area. It is marked by a rapid drop of average temperature well below the averages of a region within a 24 hour period. They can be accompanied by significant winter weather events, such as blizzards or ice storms. And they can feel even colder during periods of high winds.
Cold waves can have negative impacts on people, crops, properties and services. They are a serious problem in northern latitudes, where very low temperatures can be reached in a few hours and extend over long periods. Accidental cold exposure occurs mainly outdoors, among socially disadvantaged people (alcoholics, homeless), workers and the elderly people in temperate and cold climates. Living in cold environments in polar regions is associated with acute risk from frostbite and hypothermiahypothermia
is a condition in which the human body temperature drops below 35 ° C. As a result, the normal metabolism and functioning of the body is hampered.. In countries with populations well adapted to cold conditions, cold-waves can still cause substantial problems if electricity or heating systems fail. The cold waves invasion in countries with warmer climates can also affect human health. Cold waves can cause icing on the outer surface of the aircraft. Vehicle batteries have difficulty starting the engine, and diesel fuel is gelled in extremely cold weather. The invasion of atypical cold frost in the spring compromises the flowering of fruit trees.
There are a number of meteorological phenomena associated with cold waves:
- A polar vortex is a large-scale cyclone located near either of the geographical poles.
- A blizzard is a severe snowstorm caused by strong continuous winds of at least 60 km/h and lasting for a prolonged period of time – typically three hours or more. A ground blizzard is a weather condition where snow is not falling but loose snow on the ground is lifted and blown by strong winds.
- An ice storm is associated with the phenomenon of freezing rain, which occurs when rainfall in the form of rain passes from a warm air mass to a relatively cold air mass with an air temperature below 0°C. Raindrops, which maintain their liquid state at sub-zero temperatures, are very cold and when they reach the earth's surface, whose temperature is also below 0°C, the ground freezes. Winter storms, which cause the phenomenon of freezing rain, are often called ice storms.
- Snow is a type of precipitation occurring in the form of crystalline ice and consisting of a multitude of snowflakes that fall from clouds. Snow may be classified as dry, wet or compacted.
- An air mass is a concept associated with a huge volume of air covering hundreds or thousands of square kilometers of land, which has approximately the same temperature and humidity everywhere. Air masses are classified by their region of origin: arctic, antarctic, polar, tropical or equatorial; as well as by the route they follow: continental or maritime. As a general rule, arctic and polar air masses are cold, while tropical and equatorial air masses are relatively warm. Continental air masses are generally dry because they give up most of their moisture while travelling over the land; in contrast, maritime air masses pick up moisture during their passage over the sea and are relatively moist.
