If you read German reports about the recent flooding disaster in the southern part of the country, you will likely come across mention of "Vb weather conditions."

These conditions, which are seldom reported in English-language media, were first described in 1891 by German meteorologist Wilhelm Jacob van Bebber, who cataloged typical paths of low-pressure systems and labeled them with Roman numerals.

Although the terms Va, Vc and Vd have since fallen out of popular usage, Vb (pronounced five-B weather conditions, V = Roman 5) is still used by meteorologists to describe a rare pressure system that can bring heavy rainfall, and often catastrophic damage, to Europe.

In Europe, weather is often determined by low pressure systems that move across the continent from west to east. In a Vb weather situation, however, the path of the low pressure system changes: The low pressure system moves towards the Mediterranean Sea due to colder air masses over western Europe.

Depending on the position of the core, such low........

© Deutsche Welle