It is a high-pressure front trapped between two low-pressure systems. Essentially, it is a "dome" of warm air pressed down over the continent.
Heat and humidity together are unpleasant even when temperatures remain below the threshold of tolerability. However, if temperatures rise to historic highs as is happening in much of Europe, the combination of heat and humidity becomes deadly (literally). Currently, France, Spain, and Great Britain are suffering the worst consequences, with temperatures approaching record levels, over 37.7 degrees on average.
Everyone is blaming Super El Niño, which, poor thing, has only a tiny part of the responsibility (guess who is mostly to blame? If you answered “humans,” you guessed right). In reality, the extreme climate event that has hit Europe in the last two weeks has been known for some time and has a precise name: it’s called omega block and takes its name from the shape this configuration assumes on weather maps, similar to the Greek letter omega, indeed. The omega blocks form when a strong high-pressure system gets trapped between two nearby low-pressure systems. This translates into a huge heat dome from which nothing and no one can escape, as we are realizing.
As Euronewswrites, due to their size, the omega blocks can be quite persistent. The one over Europe acts like a lid, trapping a stagnant mass of warm, dry air coming from the Sahara and compressing it relentlessly downward. This means that the impact of this heat dome will be both intense and prolonged, with temperatures at the limit of unbearable lasting several more days. If extreme heat is dangerous in itself, when such high temperatures combine with high humidity, conditions can quickly become life-threatening. Sweat, which normally serves to cool the body, loses its effect as it evaporates, which is also slowed down by humidity, increasing the risk of heat-related illnesses. Today, due to climate change, heatwaves are capable of generating higher temperatures and humidity levels, and these phenomena will become increasingly dangerous with the rise in Earth’s temperature. Europe is warming at more than double the global average rate. Consequently, the current heatwaves are nothing but a preview of the future to come.
This is demonstrated by research from World Weather Attribution, which analyzed climate data from 854 cities in 30 European countries.
