Atmospheric River

By

Much like a river is water moving over land, an atmospheric river is a stream of water vapor moving in the sky.

When you think of the atmosphere, you probably think of gases like nitrogen and oxygen—the air we breathe. But did you know the atmosphere can hold an entire river of water too?

Atmospheric rivers are long, flowing regions of the atmosphere that carry water vapor through the sky. They are about 250 to 375 miles wide and can be more than 1,000 miles long. Rivers on land generally flow downhill; atmospheric rivers flow in the direction of moving air created by weather systems.

In general, they pick up water vapor from the warm, moist air of tropical regions and they drop the water over land in cooler regions as rain or snow.

How do atmospheric rivers form?

Infographic demonstrating rising moist air in the tropics that results in heavy rain and snow over land.

Atmospheric rivers begin as rising moist air in the tropics and result in heavy rain and snow over land. Credit: NOAA

Atmospheric rivers usually begin over tropical regions. Warm temperatures there cause ocean water to evaporate and rise into the atmosphere. Strong winds help to carry the water vapor through the atmosphere. As atmospheric rivers move over land, the water vapor rises up farther into the atmosphere. It then cools into water droplets, which fall as precipitation.

One well-known atmospheric river called the “Pineapple Express” picks up warm, moist air near Hawaii. When the Pineapple Express hits land in the Western United States and Canada, it can cause heavy rain and snow. In California, it can cause up to 5 inches of rain in a day.

Animation of an atmospheric river bringing heavy rain and snow to California.

This animation captured by NOAA’s Geostationary Operational Environmental Satellite (GOES) West from February 13, 2019, shows an atmospheric river bringing heavy rain and snow to California. Credit: NOAA/CIRA

What kind of weather is caused by an atmospheric river?

If you hear your local meteorologist talking about an atmospheric river, you can probably expect lots of rain or snow in the forecast. Atmospheric rivers are fairly common in winter in the Western United States. In fact, just a few atmospheric river events each year cause up to half of the annual precipitation on the West Coast.

Image of a conveyor belt of clouds and moisture stretching across the Pacific.

An atmospheric river that drenched California with heavy rain and mountain snow on February 14, 2019, triggering flash floods, mudslides and winter storm warnings in the Sierra Nevada. The conveyor belt of clouds and moisture stretching across the Pacific can be easily seen in this image from NOAA's GOES West satellite. Credit: NOAA

These dumps of rain and snow from atmospheric rivers are an important source of fresh water for the West Coast. However, sometimes this heavy precipitation—which can park over a region for several days—can lead to flooding, mudslides and other disasters.

Photo of a bridge over the raging South Yuba River.

Visitors at a bridge over the South Yuba River in Nevada City, Calif. during the atmospheric river event across Northern California on January 9, 2017. Credit: Kelly M. Grow/California Department of Water Resources (CC BY-NC 2.0)

National Oceanic and Atmospheric Administration, U.S. Department of Commerce

Comments

Post a Comment

Popular posts from this blog

Russian parliament passed a bill to revoke its ratification of the Comprehensive Test Ban Treaty

By
Relevance:  Russia revokes ratification of nuclear test ban treaty (CTBT) - ICAN But it affirmed that it will  retain its cooperation with the treaty’s verification system and implementing organisation.  Comprehensive Test Ban Treaty: The Comprehensive Test Ban Treaty (CTBT), which opened for signature in 1996, was intended to prohibit all nuclear weapon test explosions. Over 2,000 nuclear tests occurred between 1945 and 1996: the United States (1,000+), the Soviet Union (700+), France (200+), the United Kingdom and China (45 each). As at January 2013, 183 countries had signed the Treaty, of which 158 have also ratified it, including three of the nuclear weapon states (France, the Russian Federation and the United Kingdom). However, 44 specific nuclear technology holder countries must sign and ratify before the CTBT can enter into force. Of these, eight are still missing: China, Egypt, India , Iran, Israel, North Korea, Pakistan and the US. India , North Korea and Pakista...
Read more

Interstellar space and Interstellar Probes ( Voyager and New Horizons Missions )

By
Interstellar Space: Interstellar space is often called the space between the stars, but more specifically, it’s the region between our Sun’s heliosphere and the astrospheres of other stars. Our heliosphere is a vast bubble of plasma – a gas of charged particles – that spews out of the Sun. This outflow is known as the solar wind. The bubble surrounds the Sun and stretches beyond the planets. Both Voyager spacecraft had to travel more than 11 billion miles (17 billion kilometers) from the Sun in order to cross the edge of the heliosphere. This bubble is moving through interstellar space as the Sun orbits the center of the Milky Way galaxy. As our heliosphere plows through space, it creates a bow wave, like the wave formed by the bow of a ship. Kuiper Belt &  Oort Cloud: The Kuiper Belt is a doughnut-shaped ring of icy objects around the Sun, extending just beyond the orbit of Neptune from about 30 to 55 AU. Similar to the asteroid belt, the Kuiper Belt is a region of leftovers f...
Read more

ISRO developing semi-cryogenic engine working on LOX Kerosene propellant

By
ISRO is developing a 2000 kN thrust semi-cryogenic engine working on an LOX Kerosene propellant combination for enhancing the payload capability of LVM3 and for future launch vehicles. Liquid Propulsion Systems Centre (LPSC) is the lead centre for the development of semi-cryogenic propulsion systems with the support of other launch vehicle centres of ISRO. The assembly and testing of the propulsion modules were done at the ISRO propulsion complex (IPRC), Mahendragiri. As part of the engine development, a pre-burner ignition test article, which is a full complement of the engine power head system excluding the turbopumps is realized. The first ignition trial was conducted successfully on May 2, 2024, at semi cryo integrated engine test facility (SIET) at IPRC, Mahendragiri, which was dedicated to the nation recently by the honorable Prime Minister of India. Smooth and sustained ignition of the preburner is demonstrated which is vital for the starting of the semi-cryogenic engine. Semi-c...
Read more