Atmospheric River

• California, US is currently grappling with an extraordinary weather phenomenon known as an Atmospheric River also called Pineapple Express Storm, which has the potential to unleash up to 8 trillion gallons of rain over the state

What is an Atmospheric River?

• About:
• The atmospheric river is a long, narrow band of moisture-filled air that transports significant amounts of water vapor from the tropics to higher latitudes.
• The Atmospheric River is often associated with mT (Maritime Tropical) air mass.
• When these rivers make landfall, they release this moisture as intense precipitation, which can manifest as either rain or snow depending on the altitude and temperature.

Pineapple Express:

• The “Pineapple Express” is a well-known example of atmospheric river storms that bring heavy rainfall to the US West Coast, particularly California.

Significance:

• They play a crucial role in replenishing water supplies, particularly in regions like the western United States. The heavy precipitation they bring can contribute significantly to reservoir levels, helping to alleviate drought conditions and ensuring water availability for agricultural, industrial, and domestic use.
• Given their importance for water supply, understanding atmospheric rivers is essential for effective water resource management and planning. This includes strategies for water storage, flood control, and allocation of water resources to meet various demands.

How Common are Atmospheric Rivers, and Where do They Occur?

• They’re not limited to the US West Coast; they can occur worldwide. These rivers of moisture can stretch thousands of miles and affect regions like the UK, Ireland, Norway, and China.
• Atmospheric rivers often make the rainy season in China, known as Mei-Yu season, even worse.
• While they only account for 17% of storms on the US West Coast, atmospheric rivers contribute significantly to California’s precipitation, snowpack, and major floods. They’re predictable and can be forecasted up to a week in advance.

Practice Questions for Prelims

Which of the following best defines an atmospheric river?
A) A meteorological phenomenon characterized by a swirling mass of air with low pressure at its center.
B) A narrow corridor of concentrated moisture in the atmosphere, capable of producing heavy precipitation.
C) A long-lasting high-pressure system that typically brings clear skies and dry weather to an area.
D) A localized wind pattern formed by the interaction of mountain ranges and coastal terrain.

Ans. B

Mains Practice Question

Analyze the role of atmospheric rivers in influencing water resources management, flood risk, and drought mitigation strategies. Propose measures to enhance preparedness and resilience to the impacts of atmospheric rivers in vulnerable regions.

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