Recent storm seasons are a bit “calmer”, but phenomena, when they do appear, become extreme much more often, believes scientist Artur Surowiecki from the University of Warsaw. This may be the result of a number of different factors.
In the last several years, we have been observing a trend in Poland of a slight, but still, decrease in storm activity. – However, if they do occur, the phenomena can become extremely intense – said Artur Surowiecki, a researcher of dangerous weather phenomena from the University of Warsaw and president of the Skywarn Polska association (Polish Storm Hunters).
He added that this is mainly due to the process of climate warming.
– Between the Arctic Circle and the subtropical climate zone, i.e. the south of Europe, the thermal gradient, i.e. the difference in temperature of air masses, decreases. The consequence is a decrease in wind speed, i.e. lower dynamics of air flow in the troposphere over the central part of Europe, and therefore also in Poland. Strong and well-developed thunderstorm systems require the simultaneous occurrence of atmospheric instability, as well as a sufficiently large variation in wind direction and speed between individual levels of the troposphere. And since the state of equilibrium of the unstable atmosphere is less often connected with the dynamic flow of air masses, strong winds are formed less often. storms he explained.
Other factors contributing to the less frequent formation of thunderstorms are: lack of moisture (due to the presence of higher temperatures, the difference between the air temperature and the dew point temperature increases) and blocking atmospheric convection (i.e. rising warm and moist air portions from which storm clouds develop) by temperature inversion in the lower part of the atmosphere (when the temperature increases with altitude, not decreases, which is the norm).
A season different from the previous ones
According to Surowiecki, this year’s storm season has been “quite calm” so far compared to previous years. – In general, compared to the last few decades, not much has happened. On the one hand, it’s good, but on the other hand, it’s very puzzling why there are fewer storms than usual – he said.
One possible reason is the record warm year across the globe. – Of course, the rate of global temperature increase is primarily influenced by human activity, but not only. For example, a year ago there was a gigantic volcanic eruption in the Pacific, which caused the release of huge amounts of water vapor into the stratosphere, which will remain there for several years. As water vapor is a greenhouse gas, the effect of increasing global warming is and will be visible. In addition to air temperature, the temperature of the oceans is also exceptionally high, for example, the Atlantic Ocean is record warm this year – said Surowiecki.
Surowiecki studies dangerous atmospheric phenomena accompanying storms. – At the moment, the subject of my research are mesoscale convection systems, or storm supercells, which are the cause of dangerous accompanying phenomena such as torrential rainfall, large hail, hurricane gusts of wind or tornadoes. I study these phenomena in Poland and Europe, assessing their frequency, trends of changes in frequency and severity – he described.
In the study of storms, he is most fascinated by the dynamics of these phenomena. – For example, in recent days I have seen how a threatening storm ahead of me suddenly weakened and then disappeared, and the sun came out from behind the clouds. Trying to explain the reasons for the behavior of these phenomena is extremely interesting to me – he said.
Lots to discover
When asked whether scientists know more than they don’t know about storms, he opted for the second option.
– We still don’t know enough about thunderstorms, since we can’t even predict the exact intensity and location of convective systems 24 hours in advance. Of course, we must note here that these are point phenomena covering small areas, and in fact the result of the numerical weather model only tells us about the probability of, for example, the place where a potential storm will develop. However, if the model predicts a storm system with specific characteristics in one place, and eventually it develops several dozen kilometers away and with other characteristics, it is still far from perfect. New methods of modeling the state of the atmosphere, based, among others, on multidimensional neural networks, give hope for improving this state of affairs – he concluded.
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