Tech & Science dictionary

atmospheric river

[ at-muhs-fer-ik riv-er ]

What is an atmospheric river?

An atmospheric river is a long, thin stream of water vapor that moves through Earth’s atmosphere.

The term likens the phenomenon to a river due to the similarity in the flow of moisture from one place to another. However, the water in an atmospheric river is in the form of water vapor, as opposed to the liquid water that constitutes rivers.

Atmospheric rivers typically begin in the skies over tropical areas and their direction and movement is determined by wind and weather patterns. Once an atmospheric river reaches an area that’s cold enough, the water vapor cools and condenses, resulting in rain or other forms of precipitation.

Atmospheric rivers are a common atmospheric feature of Earth’s climate. There are usually more than 10 of them in the atmosphere at any given time, and they often occur in roughly the same patterns. One of the more well-known examples of an atmospheric river, nicknamed the “Pineapple Express,” spans from Hawaii to the western portion of the United States and Canada.

Atmospheric rivers usually only gain mainstream attention when they release significant precipitation, especially when that precipitation causes flooding or contributes to other natural disasters, such as mudslides.

Example: The weather report said that an atmospheric river is expected to bring some much-needed rain to the region.

Related words

snowpocalypse, climate crisis, murder hornet

Where does atmospheric river come from?

view of dark rain clouds with lightning flashing between them, blue filter.

The coining of the term atmospheric river can be traced to the Massachusetts Institute of Technology climate scientists whose research was responsible for the first descriptions of the phenomenon in the early 1990s. The name likens the phenomenon to a river because of the similarity in the transport and flow of water.

Examples of atmospheric river

Some really proper Oregon rain here tonight. An atmospheric river off the Pacific, rain even the English would respect. A beautiful thing
@Mr_Completely, January 13, 2021
An "extreme" atmospheric river was barreling into the Pacific Northwest on Monday, and with it will come the threat of flooding and avalanches, forecasters say.
Doyle Rice, USA Today, February 28, 2022

Who uses atmospheric river?

The term atmospheric river is typically used by climate scientists and meteorologists, though it occasionally gains mainstream attention during major precipitation events related to the phenomenon. People who live in areas commonly affected by atmospheric rivers, such as the West Coast of the US, are more likely to be familiar with the term.

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