FIT’s Pallav Ray finds that incorporating a variable called Qp to account for how precipitation cools land surfaces could improve the accuracy of rainfall predictions and help prepare for flooding during India’s monsoon season. The variable reflects the specific heat of rainwater, density of rainwater, rate of rain, surface temperature, and temperature of raindrops when they hit the surface.

Raindrops are typically cooler than the surface, so when it rains, the surface cools. In India, Ray says, most models overestimate precipitation. His team’s results generated predictions that are much closer to observed rainfall. “The moment we include that term, it cools down the surface, land surface. The temperature difference is smaller between the land and the ocean,” says Ray. “That reduces the overall precipitation overland because now less moisture is coming from the ocean.”

• Pallav Ray