Physical Geography
Atmospheric River
▪ In April 2025, a large part of the US experienced heavy rain, strong winds, and severe thunderstorms due to a meteorological phenomenon known as an Atmospheric River (AR).
▪ Definition: An atmospheric river is often described as a “river in the sky”. It refers to a relatively long and narrow band in the atmosphere that transports enormous amounts of water vapor from the tropical oceans to continental regions. Unlike rivers on Earth, they are not visible.
▪ The “Pineapple Express” is a well-known example of AR storms that bring heavy rainfall to the US West Coast, particularly California.
▪ AR in India: A study found that between 1951 and 2020, India experienced 596 major atmospheric river (AR) events, with over 95% occurring during the summer monsoon season (June to September).
✓ Notably, 70% of major floods from 1985 to 2020 were linked to ARs, including the devastating 2013 Uttarakhand floods, 2018 Kerala floods, and 2007 South Asian floods.
✓ The frequency and severity of ARs have increased in recent decades, particularly in the IndoGangetic plains and peninsular India, leading to significant destruction and loss of life.
