New study reveals one-fourth of India's monsoon rain evaporates mid-air in Western Ghats

A new study by the Indian Institute of Tropical Meteorology (IITM), Pune, reveals that nearly a quarter of the rain falling over the north Western Ghats during the southwest monsoon evaporates mid-air. This is the first observational estimate of raindrop evaporation over India, with the actual amount varying from 4%-61% daily. The evaporation process cools the sub-cloud layer, feeds downdrafts, and creates cold pools, reshaping convection and affecting rainfall predictions. Researchers used isotope ratios in rainwater and atmospheric vapour, read by a laser spectrometer, and a one-dimensional Below Cloud Interaction Model to calculate the evaporation rate. This finding is crucial for refining climate and monsoon models.

Key Points

  • Approximately 25% of monsoon rain over the north Western Ghats evaporates mid-air, according to an IITM Pune study.
  • This is the first observational estimate of raindrop evaporation in India, with daily variations from 4% to 61%.
  • Mid-air evaporation impacts atmospheric convection, cooling the sub-cloud layer, and influencing rainfall patterns.
  • The study utilized isotope ratios in rainwater and atmospheric vapour, along with a Below Cloud Interaction Model, for its measurements.

Exam Facts

  • Research institute: Indian Institute of Tropical Meteorology (IITM), Pune.
  • Region studied: North Western Ghats.
  • Evaporation percentage: Approximately 25% (ranging 4%-61%).
  • Journal published in: Atmospheric Chemistry and Physics.

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All current affairs of 12 July 2026