Just another heavy downpour? Nope, this is officially an ‘atmospheric river’
It may not help, as you drive around in vain looking for passable lanes or, God forbid, wait for waters to recede from your living room, to know that the weather system behind the floods has a rather wonderful name. The likely culprit is a mega “atmospheric river” – a massive flow of vapour, low in the atmosphere – a US scientist has told the Financial Times. The term, only categorised by the American Meteorological Society in 2017, is surely due some wider appreciation.
An “atmospheric river” is not, as you might imagine, a broad, misty watercourse dotted with herons and punts.
It is defined, officially, as “a long, narrow and transient corridor of strong horizontal water vapour transport”.
This huge vapour flow extends from the ground up to around four miles high and shifts, on average, double the flow of water carried by the Amazon. Naturally, climate change is thought likely to make them bigger, so we can look forward to more of the same.
Their definition is the product of a fierce debate among meteorologists, according to an account in the Bulletin of the
American Meteorological Society. Before its codification, some naysayers argued that the term was superfluous, since they could just as well be described as “warm conveyor belts”, notwithstanding that this phrase brings to mind a soup factory rather than a powerful, airborne watercourse.
Others were concerned about whether to retain the link to “extratropical cyclone-related dynamics”
The likely culprit is a massive flow of vapour, low in the atmosphere
or whether to allow for tropical usage. This hot topic was in the end only resolved by the use of two town hall meetings and several sessions of the International Atmospheric Rivers Conference.
For us regular weather consumers, it is at least a relief to know that the weatherman has a name for what is happening to us, even if the net result is that we are going to get soaked, again.