Study delivers new knowledge on thunderstorms and heavy rain — ScienceDaily


Thunderstorms are weather disturbances characterized by concentrations of thunder, lightning and fierce winds.

When they accumulate in clusters, these storms are often accompanied by violent cloud bursts and flooding, which can devastate the areas affected.

Denmark is no stranger to this phenomenon. In 2011, large parts of Copenhagen were submerged by deluges that lead to roughly 6 billion kroner in damages reported to insurance companies.

In a new study, researchers from the University of Copenhagen shed light on one particular mechanism that has the potential to spawn powerful thunderstorms and cloud bursts:

“We conclude that the atmosphere’s ability to generate large thunderstorms is influenced, among other things, by the difference between the temperature of the earth’s surface during the night versus during the day. If the difference is great, we see more thunderstorms, and subsequently, more cloud bursts,” explains Jan Olaf Härter, an associate professor at the University of Copenhagen’s Niels Bohr Institute.

Along with his department colleagues, Härter used computer simulations to study the occurrence of so-called mesoscale convection systems — particularly powerful thunderstorms that spread out over areas of 100 kilometers or more.

While these types of thunderstorms occur mainly in the tropics, they are also relevant in the Danish context.

“If summertime temperatures in Denmark continue to increase, I would not be surprised if we experience more thunderstorms and cloud bursts. And this is exactly what some climate models predict will occur within the next 20-30 years,” says Jan Olaf Härter.

The significance of night- and daytime temperature differences

Thunder occurs when warm, moist surface level air rises into weather and meets cooler air higher up in the atmosphere.

This destabilizes the air above it even more and creates convection, which transports the warm air even higher.

It’s like a pot of boiling water — heated water