Atmospheric physics explains increasing summer hail intensity

Extreme summer hail storms are becoming more destructive due to increased atmospheric energy. While ice is typically associated with winter, summer storms are fueled by intense solar radiation, accumulated thermal energy in the ground, and high evaporation rates in the lower troposphere.

Surface heat and marine humidity generate powerful updrafts exceeding 150 kilometers per hour, which can sustain large masses of ice in the air. According to the Clausius-Clapeyron equation, for every one-degree Celsius increase in temperature, the atmosphere can hold approximately seven percent more water vapor. This warmer atmosphere acts as fuel for more violent storms.

A study by the Complutense University of Madrid and AEMET analyzed a significant hail event in Girona in August 2022, concluding that extreme surface heat is essential for sustaining large ice masses before they fall. While a warmer atmosphere may melt smaller hail before it reaches the ground, it facilitates the formation of much larger, intact hailstones that cause significant damage to vehicles and buildings.