The risk of tornadoes is higher than previously thought

The risk of tornadoes is higher than previously thought
The risk of tornadoes is higher than previously thought

Russian climatologists, together with foreign colleagues, have collected and analyzed data on tornadoes over the territory of northern Europe over the past 11 centuries. Scientists managed to find some patterns on the basis of which it is possible to assess the risk of tornadoes in a particular area and calculate the potential damage that it will cause. It also turned out that tornadoes are a much more frequent phenomenon than is believed. The results of the work were published in the Monthly Weather Review magazine. The studies were supported by the Presidential Program of Research Projects of the Russian Science Foundation (RSF).

“We have collected data on tornadoes on the territory of Russia and neighboring countries since the 10th century, and counted almost three thousand phenomena, and this is not counting the fact that the data is far from complete. We have seen an increase in the number of tornadoes in recent years, associated with the growth of information. Now we have already reached the figure of 150 cases per year, of which about 10–20 are strong tornadoes, the wind speed is more than 50 m / s, and 1-3 tornadoes are destructive, with a wind speed of more than 70 m / s. But of course, most of the phenomena are weak and short-lived. Nevertheless, on average, from 2 to 10 people die from tornadoes in Northern Eurasia per year, from 10 to 100 people receive various injuries, "says Alexander Chernokulsky, the project manager for a grant from the Russian Science Foundation, Ph. D. in physics and mathematics, senior researcher at the Institute. Atmospheric Physics named after A. M. Obukhov RAS, laureate of the Moscow Government Prize for Young Scientists, laureate of the RAS Prize for Young Scientists.

Climate change worries many: under the new conditions, some ecosystems with their inhabitants may disappear, a change in water and temperature regimes will affect the economy, for example, agriculture in African countries, and much more. Another of the consequences is an increase in the number of natural hazards. And since the fight against climate change is not so easy, it is necessary to adapt to it and develop ways to reduce the damage from various disasters.

An international group of climatologists has studied information about an underestimated natural phenomenon - tornadoes. They are rapidly rotating vortices that arise in thunderstorm clouds of a special type - not in small, short-lived ones, but in rather extended ones, with their own circulation, the so-called mesocyclone. Warm, humid air rises upward, forming a low pressure area, into which the cold air surrounding the funnel rushes. In the process, a large amount of energy is released, which is spent on the movement of the tornado. The funnel descends in the form of a trunk to the surface of the earth or water, and after the exhaustion of the supply air, it weakens and is drawn into a thundercloud. In the lower cross-section, the tornado can reach a diameter of several hundred meters and even several kilometers and move at a speed of up to 70 km / h. Tornadoes are observed on all continents with the exception of Antarctica, but most of all - in North America, where about a thousand tornadoes (tornadoes) arise per year; according to official data, in our country during the same time there are only one or two, mainly in the European part of Russia. As it turned out, the figure is greatly underestimated.

Scientists found information about tornadoes in a variety of sources: historical chronicles, news stories, eyewitness accounts, meteorological observations, and so on. However, not all cases can be recorded: if the phenomenon took place in the distance (for example, in the Siberian taiga), no one could see it, and rare observation stations could not record. Therefore, the researchers also analyzed satellite images from different years and identified areas of specific, "swirling" felling - so the number of cases increased.

Based on the available data, it was possible to conclude that tornadoes have a clear time reference. So, the peak of their occurrence over land falls on May-August and 17-18 hours of the day; above water, it shifts to late summer and the first half of the day, 9–13 hours. The first can be explained by the peculiarities of heat transfer: the maximum heating of the surface is observed in the region of 3-4 pm, then the development of a thundercloud takes some time. The second is associated with the strong evaporation of water from the sea surface - warm moist air is necessary for the formation of a tornado.

Climatologists have also proposed an “ingredient” approach to predicting the risks of tornadoes. The bottom line is that any dangerous natural phenomenon consists of several factors (humidity, temperature, and so on) and is associated with their critical change. That is, having recorded sharp jumps in indicators (according to observation data or in weather forecast models), it is possible to take measures to protect the population and important objects. Modeling according to this principle, taking into account climate change, showed that the risk of tornadoes in the coming years will greatly increase in the south of the Far East, and also (to a lesser extent) in the middle zone and Siberia. However, monitoring the weather and introducing tornado forecasting into operational practice can significantly reduce the destructive effect and save many lives.

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