Atmospheric Rivers

Context: 

Recently, a dangerous storm blew in California, USA. It threatened coastal areas and caused flooding and mudslides 

Atmospheric Rivers Hit California With Flooding

• This storm is also known as a “Pineapple Express”.
  • It is named “Pineapple Express”because it brings moisture from the tropics near Hawaii across the Pacific over to the West Coast of the US. 
  • A Pineapple Express is a type of atmospheric river that can affect the entire west coast of North America, resulting in extreme rainfall, excessive flooding, property damage, and disrupted travel.

What is an Atmospheric River?

• An atmospheric river is a plume of moisture, or water vapor, that moves from the tropics and is dumped over a region as heavy rain or snow. 
• Atmospheric rivers are narrow bands that tend to occur on the eastern side of strong mid-latitude storms.
• It usually causes heavy precipitation and rainfall when it hits the land region. 

Atmospheric Rivers Impact in India

• India has also seen its impact during 1985 and 2020.
  • During this period, India’s 70% flooding was due to atmospheric rivers. 
• Weather events like 2013 Uttarakhand flood and Kerala flood in 2018 were also triggered by this. 
• The southern region of western ghats and eastern ghats of India face major issues like heavy rainfall and precipitation. 

Reasons For Rise in Atmospheric Rivers In India

• In India, its formation is largely caused by sea surface temperature in the south-central Indian ocean. 
  • Evaporation has increased in the Indian ocean due to higher Vapour Pressure Deficit (VPD).
    • VPD is a measurement unit that measures the pressure needed to turn liquid into vapor. 

News Source: PIB

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