GS 1 | World Geography

Why in the news?

  • A large part of the United States witnessed heavy rain, strong winds, and severe thunderstorms due to an atmospheric river, which caused widespread disruption.

Atmospheric River

  • Definition: Narrow, fast-moving bands of moisture in the atmosphere transporting large amounts of water vapour — akin to rivers in the sky.
  • Typical Dimensions:
    • Width: 400–600 km
    • Length: 1600+ km
  • Common in: Mid-latitude regions (e.g., US West Coast).
  • Formation:
    • Originate over warm tropical oceans.
    • Directed by low-level jet streams and cold fronts of extratropical cyclones
  • Impact of Atmospheric Rivers
    • Positive:
      • Crucial for rainfall and water supply, especially in drought-prone regions.
    • Negative:
      • Can cause flooding, mudslides, cyclone-like winds, and wave surges.
      • Example: Dec 2010 – US West Coast received 11–25 inches of rain from a series of atmospheric rivers.
  • Pineapple Express
    • A well-known atmospheric river bringing moisture from around Hawaii (tropical Pacific) to the US/Canada West Coast.
    • The recent storm in the US originated in the Caribbean, not from the Pineapple Express.
  • Implication of Climate Change
    • Increased intensity of atmospheric rivers (not necessarily frequency).
    • More severe precipitation, flooding, and weather extremes.

 

Source: Indian Express