polar depression - a natural formation.These natural systems provide and identify using conventional meteorological messages are not so simple.Therefore, they are a threat to mariners, air carriers and other human activity in the northern regions.As far as unpredictable and dangerous polar depression, which this phenomenon, let us step by step.
History detection
polar depression - a phenomenon that relates to weather systems are relatively small scale, which is short-lived and is characterized by low pressure.Formed over the oceans in both hemispheres at the side of the main polar front.Early studies suggested that the main reason for its occurrence - thermal instability.But this statement was very far from reality.Later we studied the conditions of formation.For the first time this type of natural system was found on the meteorological images that became available in the 60s of the last century.
At high latitudes experts was definitely a whole lot of eddy clouds.They were traced over the ice-free areas mentioned above seas, over Labrador, as well as the Gulf of Alaska.It is noticed that the polar depression dissipates quite rapidly at landfall.Northern counterparts Antarctic cyclones generally weaker, because all along the continent are experiencing drops of different temperatures.Although sometimes even within the Southern Ocean can be observed dynamics of this phenomenon.
Satellite images suggest that the polar depression is characterized by a variety of cloud shapes that can be formed from the spiral bands of clouds enveloping the center or closer to the polar front to take the image of a comma.In fact, the structure depends on the degree of danger of the weather, the intensity and speed of propagation.
formation mechanism
When the polar front wave starts its development, facilitates the penetration of the flow of tropical air mass on Wednesday, produced the polar depression.Given the advancement of the east, warm cyclone, whose air is trying to displace the cold, is different from the opposite that follows and rolls under the sun warmed the masses.The result of this move opposite elements becomes the pressure drop on the surface, the center of which is surrounded by isobars that are blown by wind across.
As a result, air flows to the core of depression and up the spiral overnight.With the development of this process, a cold front approaches the heat, which leads to the occlusion phase.Despite the presence of air with a low temperature at the top of the cyclonic motion and character, at which point isobars and wind direction, on the surface there is a contrast in the form of a front dividing line between the incoming flow in the rear area of depression.This leads to the transformation of the front end.Depending on the nature of the processes that determine such a metamorphosis, occlusion is either cold or warm.It depends on the external manifestation of the cyclone on the land.
Lifetime
period of existence of this kind of weather system depends on how long the potential energy is transformed into kinetic energy.Polar Depression destroyed when the air between the layers, located next door, disappears the contrast of high and low pressure.Its rapid weakening occurs when the displacement of the ice surface or when approaching land.Given the direct relationship with the rise of air and strong winds, it can significantly influence the weather.
weather modification
As the air rises gradually warm fronts, as long as it reaches stability, the formation of layered cloud forms.If the sky cirrus clouds appear, then the warm front side.As it approached the clouds are lower and more massive.Often bedding portends fine rain over time turns into a heavy downpour.And for dinner, you can already expect a sunny sky in cumulus frame.
arrival of a cold front the weather suddenly changes.In the heavens there are cumulonimbus clouds, like the tower, bringing, as a rule, heavy showers and thunderstorms.Suddenly, the wind direction changes to north or north-west.Stormy situation develops unexpectedly and within a short period.
What is the difference?What is the difference
frontal depression in the southern hemisphere by itself like in the North?Almost nothing, but there is one important dividing line.In the first case, the wind turns on the warm front from the north to north-west, and in the cold - from west to south-west, in the second - the movement is the same as that of the arrows on the clock.But the feature that each polar depression - a phenomenon the individual, that is, there is no ideal model that is able to describe it.
Opportunity
forecasts predict the weather in the frontal depressions may be on the condition that a large area covered by synoptic observations.For example, in the European part of the mainland area of research is to expand to the west, including the adjacent areas of the Atlantic.After all, these natural systems usually have a speed of 1,000 km per day.If the observations are carried out in the upper layers of the atmosphere, it will greatly facilitate the work on the outlook in the sector, where the cyclone.
quite common when the frontal depression are connected in the big family, involving secondary education movement around the main flow.The most common are those that appear at the edge of the cold air.Each additional representative of such a symbol of the family is a path closer to the equator than its predecessor.
