Microphysics of clouds and rain over the Western Ghat

Shallow clouds over the Western Ghats produce heavy rainfall due to rapid condensational growth of cloud droplets, driven by orographic updrafts. Research reveals that collision-coalescence processes dominate rain formation, with distinct raindrop size distribution (DSD) patterns observed on both windward and leeward sides of the mountains. At Pune (lee side), DSD shapes transition from concave upward to downward during stratiform rain, indicating breakup processes at lower altitudes. Conversely, Mahabaleshwar (windward side) shows bimodal and monomodal DSDs for light and heavy rainfall, respectively, with small drops contributing significantly. Aircraft measurements confirm that ambient updraft speeds foster rapid droplet growth, leading to precipitation within a few hundred meters of cloud depth. These findings highlight the dynamic interplay between cloud microphysics and orographic forcing in shaping rainfall over this UNESCO-listed region.

Konwar, M., Das, S. K., Deshpande, S. M., Chakravarty, K., & Goswami, B. N. (2014). Microphysics of clouds and rain over the Western Ghat. Journal of Geophysical Research: Atmospheres, 119(10), 6140–6159. Portico. https://doi.org/10.1002/2014jd021606