The sweltering heat wave across Europe

Subject :Geography

Section: Climatology

Context:

Context: Large swathes of Europe, the U.K. and the U.S. are sweltering under extreme heat wave conditions.

What is behind the extreme heat waves?

The heat waves are a result of climate change caused by human activity.
Global temperatures have already risen by more than 1°C , and studies in the U.K. had shown that a one degree rise in temperature raises the probability of the country witnessing 40°C by ten times.
The rising global temperature, which this year led to deviations above the normal by as much as 15 degrees in Antarctica, and by more than 3 degrees in the North Pole, have also, induced changes in old wind patterns.
These changes turned Western Europe into what has been described as a “heat dome” a low pressure area that began to attract hot air from northern Africa.
In the case of the U.S., the record temperatures are being linked to changes in the jet stream — a narrow band of westerly air currents that circulate several kilometers above the earth’s surface.
While a conventionally strong jet stream would bring cooler air from the northern Atlantic, in recent years the jet stream has weakened and split into two, leading to intense and more frequent heat waves over parts of the American continent

Concept:

What is Heat Dome?

A heat dome occurs when the atmosphere traps hot ocean airlike a lid or cap.
Heat dome happens when strong, high-pressure atmospheric conditions combine with influences from La Niña, creating vast areas of sweltering heat that gets trapped under the high-pressure “dome.”
Imagine a swimming pool when the heater is turned on — temperatures rise quickly in the areas surrounding the heater jets, while the rest of the pool takes longer to warm up
If one thinks of the Pacific as a very large pool, the western Pacific’s temperatures have risen over the past few decades as compared to the eastern Pacific, creating a strong temperature gradient, or pressure differences that drive wind, across the entire ocean in winter.
In a process known as convection, the gradient causes more warm air, heated by the ocean surface, to rise over the western Pacific, and decreases convection over the central and eastern Pacific.
As prevailing winds move the hot air east, the northern shifts of the jet stream trap the air and move it toward land, where it sinks, resulting in heat waves.