Weather Thunderstorms are more severe in cities than in the countryside

Thunderstorms are more violent and more frequent in cities than in rural areas. This has been shown by researchers at the University of Lausanne in a new study. The larger the city, the greater this effect.

In addition, the spatial distribution of rainfall changes in cities, according to a press release issued by the University of Lausanne on Tuesday. While rainfall during thunderstorms is generally evenly distributed in the countryside, it is often concentrated in small areas in cities.

This increases the risk of flooding. "The threat of flooding could also intensify in the future as cities grow and global warming further intensifies storms worldwide," lead author Herminia Torelló-Sentelles was quoted as saying in the press release.

Warm cities

According to the scientists, the reason for the intensification of thunderstorms in cities is that cities are warmer than their rural surroundings. This causes air from the surrounding regions to flow into the city, where it rises and condenses into thunderclouds. According to the study, this phenomenon is intensified by tall buildings, which act as a barrier for the air masses. In addition, urban air pollution in the form of aerosols in the air could also play a role in the formation of precipitation.

For the study, which was published in the journal "Earth's Future", the researchers analyzed weather data recorded over seven years in various cities in Europe and the USA. The cities studied - Milan, Berlin, London, Birmingham, Phoenix, Charlotte, Atlanta and Indianapolis - differ in terms of their size, climate and urban planning. What they have in common, however, is their distance from mountains and large expanses of water. Both are factors that influence local rainfall patterns and can therefore interfere with the analyses.