Status: 22/09/2023, 05:52 a.m.
By: Sandra Sporer
The omega effect causes extreme weather conditions in Europe. Heat waves, continuous rain and flooding could become the new normal.
Munich – For weeks this summer, we experienced the so-called omega effect. This weather phenomenon led to several extreme weather events in Europe, from heat waves to persistent rain and devastating floods that also claimed thousands of lives. This is a threatening situation that we will probably have to adapt to, because according to a study by climate researchers, this weather situation will occur more frequently in the future due to climate change.
Omega weather conditions lead to contrasting extreme weather situations that repeatedly claim human lives. © Achilleas Chiras/dpa; Meteosat Euro-Atlantic
The weather phenomenon Omega Effect claimed thousands of lives this summer
But what is actually behind the so-called omega effect? This term is used by meteorologists to describe a phenomenon in which a blocking high-pressure area develops over Central Europe, flanked by two low-pressure areas to the east and west. As a result, the air "then has to make a big arc first to the north, then back to the south," according to a video by wetter.com explaining the phenomenon. This air current, which is visually reminiscent of the Greek letter Omega, stabilizes the weather. This allows it to remain constant for weeks.
But in the heat as well as in the cold and rain, there is a point where it becomes too much for certain regions. However, the omega position promotes such extreme weather conditions and in the middle of summer it can quickly lead to extreme heat and drought. Just like in the summer of 2023, when the highest heat warning level was declared in Italy. In the catchment area of the lows, on the other hand, storms occur more frequently and, in the worst case, floods - as recently in Spain.
So the omega effect leads to completely different weather conditions in regions that are relatively close to each other. Therefore, in Europe there was heat here, cold and storms there.
Climate change causes more frequent occurrence of the omega effect - expert predicts more extreme weather
The numerous disasters of recent months have claimed many lives. Particularly worrying is therefore the prediction by scientists that climate change will cause such extreme weather conditions more frequently in the future. The focus is on the jet stream, i.e. the west-east air flow that gets out of its orbit due to an omega weather situation. Global warming, especially the warming of the oceans, weakens it, leading to longer-lasting weather phenomena.
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The storm in Spain caused devastation and deaths. The heavy rainfall was the result of the omega effect – a weather phenomenon that we will have to deal with more in the future. © Alejandro Martínez Vélez/dpa
The study by the Royal Netherlands Meteorological Institute (KNMI) and the Potsdam Institute for Climate Impact Research (PIK) focused mainly on double jet stream situations and found that these were responsible for 30 percent of heat waves in Europe over the past 42 years. This is according to a statement from PIK on the publication of the study.
Kai Kornhuber, co-author of the study, adds: "Climate models tend to underestimate extreme weather risks. (...) It is possible that we will actually experience extreme heat waves even more often and with greater intensity than models in these scenarios already predict." (sp)
This article, written by the editors, used machine support. The article was carefully reviewed by editor Sandra Sporer before publication.