Index - Technical Sciences - Cold intrusions, polar vortex - Are we really going to have a harsh winter?

Index – Technical Sciences – Cold intrusions, polar vortex – Are we really going to have a harsh winter?

With our current knowledge and prediction models, we can make reliable predictions for only 1-2 weeks. There are also long-term models, such as seasonal models, which are based on averaged values ​​of weeks or months can be analyzed Expected weather, but here the uncertainty is much greater – we can only talk about trends, loosening of plots in some areas or an increase in frequent heat waves.

Mark Meeks, a meteorologist According to an article published one and a half times Climate change will almost certainly affect and affect the polar vortex, which is often referred to in promising news as a harsh winter — we don’t know how yet. It’s an atmospheric phenomenon, and thanks to research over the past few decades, we really know a lot about it, but its behavior is still not entirely clear to scientists.

The polar vortex is a stratospheric cyclone that is nothing more than an air vortex surrounding cold air, with a distinct seasonal periodicity: it slows down and disappears in the summer and then reappears over the poles in the winter. This is the reason for the formation of seasons: the tilt of the Earth’s axis in which the sun’s radiation does not reach the corners of the winter season. At the end of September, the Arctic “sunsets” for half a year at the end of September, causing a significant decrease in temperature – also causing a decrease in pressure at high altitudes, intensifying the counterclockwise rotation. This is called the stratospheric polar vortex in practice, and it continues in the northern hemisphere until March, when the sun rises again at the pole.

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I’ll tell you about the polar vortex!

A strong polar vortex is usually associated with warmer winters in Hungary, but then, for example, clones of a storm coming to Europe from the Atlantic could be a source of danger, according to a degree and a half. However, there are plots of land where the polar vortex weakens in a short time, the wind direction changes from west to east at high altitudes, and the stratospheric temperature rises by more than 10 ° C.

These events are called sudden stratospheric warming, which are among the most severe changes in the atmosphere. With only 40 years of reliable data, there are still open questions.

It is not yet clear what caused the sudden rise in temperatures.

Some theories link it to large anomalies in the troposphere, others link it to higher parts of the atmosphere. After these sudden warm-ups, two things can happen to the polar vortex:

  • On the one hand, you can significantly change its position (it moves from the pole),
  • On the other hand, it can split into two smaller vortices (hence the immediate effect is that lower ozone can degrade, so these warming reduces the size of the ozone hole – good news for us).

Either way, sudden warming in the stratosphere is expected to have some impact on our daily weather, but statistically speaking, the interaction occurs in only two-thirds of the cases.

Can burglaries come cold?

In the troposphere – that is, at the bottom of the atmosphere, about 8 to 12 kilometers away – the effects of sudden warming can usually be detected 2-3 weeks after the event, especially the air pressure above the pole which is astonishingly rising. This usually includes the movement of cold air masses towards low latitudes, depending on the current arrangement of the troposphere.

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According to an article written by Mark Meeks, the winter of 2020/21 was a typical example of this, when a sudden stratospheric warming on January 4 was followed by a severe cold snap in North America and Europe in February.

But it is not yet possible to say for sure when and what effects such a near-surface event will have. Just as we can’t be sure what to expect this year from the development of the polar vortex: the atmosphere is a complex system, so we can’t draw bold conclusions that we will have very cold winters just because there is a statistically greater chance of a weak polar vortex this winter.

Climate change is also affecting the polar vortex

But why is the polar vortex so important to us, should we expect to change in line with climate change? According to Mark Meeks, the short answer is yes, it’s to be expected – but the exact picture is much more accurate than that. As the concentration of greenhouse gases increases, the troposphere will continue to warm, but in the case of the stratosphere and the polar vortex above it, there is more uncertainty about the changes.

An important trend discovered in recent decades is that the so-called Breuer-Dobson cycle, which, quite simply, means the movement of matter between the troposphere and stratosphere, has been accelerated by climate change. Another important change that can already be noticed is that the Arctic Circle is warming at a faster rate than the rest of the Earth.

– Read in the first-class article and a half.

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This phenomenon, along with the speed of ice melting, can disrupt the rotation of the troposphere and stratosphere. Although there is a lot of uncertainty in this scenario, it is certain that the complex interactions between the troposphere and the stratosphere are affected by climate change, so mitigating warming will remain in our common interest, whether or not we have a harsh winter this year.

(Cover Image: Tamás Sóki/Index)

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