Flash floods resulting from extreme rainfall pose a major risk to people and infrastructure, especially in urban areas.
Flash floods resulting from extreme rainfall pose a major risk to people and infrastructure, especially in urban areas. Higher temperatures due to global climate change affect continuous rainfall and short rain showers in somewhat equal measure. However, if both types of precipitation occur at the same time, as is typical for thunderstorm cloud clusters, the amount of precipitation increases more strongly with increasing temperature, as shown in a study by two scientists from the University of Potsdam and the Leibniz Centre for Tropical Marine Research (ZMT) in Bremen. The study has just been published in the journal “Nature Geoscience”.
Extreme rainfall can cause rapid flooding, so-called “flash flooding”. How does such extreme rainfall change with temperature? This question has been studied for decades by using appropriate recordings of rainfall and temperature, measured at short intervals of one hour or less.
Rainfall and clouds form when the water vapor in the air saturates, thus forming small droplets that eventually lump together to form rain drops. According to the Clausius-Clapeyron relation, saturation requires roughly 7 percent more vapor when temperatures rise by one degree Celsius. This relation might, as an oversimplified image, be motivated by a sponge that can capture more water as temperatures increase. An extreme rainfall event in this image corresponds to squeezing the sponge to release most of its water.
Read more at University of Potsdam
Image: A thunderstorm cloud cluster and its typical shelf cloud ahead of heavy rainfall near Bremen (Germany) on 21 July 2023. (Credit: Maxime Colin)
