Rivers exist not only on land, but also in the atmosphere, and meteorologists speak of “atmospheric rivers”, basically strips of thousands of kilometers long, containing a lot of water that bring record rainfall to many places on Earth . How are these vast heavenly rivers born? Why are they little known in Romania and how does the warmer climate change them?
Where these heavenly rivers feel “at home”.
They are called “atmospheric rivers” (in English) because they are long, not very wide, but they contain huge amounts of water that reach the Earth. The longest atmospheric river documented by climatologists was more than 8,000 km long and hit the Pacific Northwest region in 2017. Most are about 2,000 km long and 800 km wide.
They are present in many places in the world, and their presence has consequences: they bring snow to East Antarctica, cause floods in Western Europe, cause terrestrial rivers to burst their banks in Australia, and all these “atmospheric rivers ” causing disasters in Australia. Western United States. But even if it doesn’t seem like it, they also have positive sides.
“They are very long strips loaded with extremely high humidity. The transport of water is something that happens often in the atmosphere, but to be an “atmospheric river” it must be at least 2,000 km long and less than 1,000 km of width. From the satellite, an atmospheric river looks like a very long and very thin strip and it looks white, because there is a huge amount of water, “explains Monica Ioniță, a researcher from Germany, to HotNews.ro. studied the subject and wrote about it, together with two colleagues (Viorica Nagavciuc and Bin Guan).
These “rivers” are very important, because 90% of the total amount of water vapor that is transported to the middle latitudes arrives there through these “atmospheric rivers”.
In California they are very frequent, they are essential for the water resource and for the snow, and the most famous atmospheric river is called “Pineapple Express” and it brings to the west coast of the USA the moisture from the area of ​​the ‘Hawaiian Islands. . More about how they appear and how they are formed you can read it here.
In California, somewhere between 25% and 50% of the annual precipitation comes from these phenomena that sometimes produce catastrophic floods, but they also have good sides, beyond the snow brought to the famous ski resorts. They can end the drought, refresh the water reservoirs and green the dry landscape. Snow is also good for agriculture.
Even in California, on average, 7 to 10 serious atmospheric rivers occur each year. A study cited on the NASA site indicates that atmospheric rivers will be larger due to global warming.
And the damage from the floods brought by these “rivers” will be greater, another shows study, published in the journal Nature.
How rivers form in the atmosphere
These phenomena are not jokes A study from the beginning of 2024 describe how they act four atmospheric rivers on the west coast of the United States. Research shows the impact that these “rivers in the sky” have on the precipitation in East Asia
These rivers form somewhere above the oceans, where it is warmer and can bring disasters especially in coastal areas, through extratropical cyclones that appear especially in the winter, explains Monica Ioniță, researcher at the Alfred Wegener Institute for Polar and Marine Research (Bremerhaven, Germany).
As an atmospheric river contains a lot of moisture, when they form and reach the west coast of America, these bands of high water “meet” the mountains and bring a lot of snow to the ski resorts.
Which areas of Europe are affected by atmospheric rivers?
In Europe it does not appear so often, except for Great Britain, Ireland, western Norway, after which they form a little more north of the tropical Atlantic, and this band of clouds with a lot of water reaches Scandinavia.
Exceptionally, these atmospheric rivers also reach Central Europe, especially the Rhine in Germany. “I make predictions about the rivers in Germany, and a few years ago there were always problems in the winter, because we did not know where we got so much water from. These atmospheric rivers can also be present in the area of ​​the Rhine, because they reach the western coast of Europe, I hit Francethey hit the mountain areas, rise and then bring a lot of rainfall. It doesn’t happen very often, but most of the precipitation in the Rhine region during winter is associated with these atmospheric rivers,” explains Monica Ioniță.
Apart from the United Kingdom and Norway, these rivers affect France, most often Spain (floods), but the limit is western Germany, because these huge gangs do not have much power to advance further to the east
Why don’t we have something like that in Romania?
Could it reach Romania? “I don’t think so and it’s better that they didn’t come,” says Monica Ioniță, but the reminiscences of these rivers can reach further than western Germany. “However, we have not really seen floods in the winter season in Romania, and this shows that these rivers have not reached the country and only in Western Europe we have many floods in the winter.”
There is also a five-step “scale” to rank atmospheric rivers from “poor” to “exceptional” based on the amount of water carried.
As with other intense precipitation events, atmospheric rivers will be affected by a warming climate, meaning that on average they will bring more rain, will be more frequent and intense, and will bring more snow.
An atmospheric river can travel up to five days over the ocean, and when it reaches coastal areas, the extreme precipitation event lasts on average about 15-20 hours, but there are also cases where some areas have been seriously flooded after to heavy rains that lasted. more than two days.
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