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Dot has only recently dug myself out from the massive snowstorm that buried the Eastern coast, so let’s consider some other weather phenomena. In this Dear Dot from the archives, a reader seeks illumination about atmospheric rivers, which had been in the news. Dot dives in:
I’ve been reading some headlines about atmospheric rivers. What exactly are they?
– Jas
Dear Jas,
Perhaps you’re referring to this headline? Or maybe this more recent one, suggesting that the incidence of atmospheric rivers could double by 2100 due to climate change? Whatever headline piqued your curiosity about atmospheric rivers, Dot is eager to elucidate.
Of course, I am no expert on weather phenomena, though I have long been fascinated by the topic. As a youngster, Dot even developed a penpal relationship with my local news station’s weather man. Alas, Bill Hutchins died in 1999, so I cannot write to him for an explanation of atmospheric rivers.
Lacking a favorite meteorologist to consult, Dot turned to Char, a student intern at Bluedot who shares Dot’s deep curiosity about weather — just like you, Jas.
For a start, Char reported, an atmospheric river is not really a river at all, in the way we think of rivers. NOAA calls them “rivers of the sky,” because they are, essentially, an accumulation of water vapor, picked up in the tropics and carried inland over mountains, where it cools and rises, producing condensation. NASA describes atmospheric rivers as “long, narrow jets of air” carrying water vapor, ranging from 250 to 375 miles wide, and averaging 1,200 miles in length. The condensation they carry is released as rain or snow.
“Atmospheric river” is a relatively new term (coined in 1994) for a phenomenon that was formerly more typically called the Pineapple Express (if it originated in Hawaii) or the Rum Runner Express (Caribbean).
Atmospheric rivers are neither necessarily dangerous nor rare (NASA says there are roughly 11 in the world at any given time). The average atmospheric river can be beneficial, providing valuable precipitation and replenishing freshwater reserves.
Curious to know more about atmospheric rivers? Keep reading.
