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Cool, sinking air from a storm cloud's downdraught spreads out across the land surface, with the leading edge called a gust front.

Accelerated winds near skyscrapers are caused by the "downdraught effect", says Nada Piradeepan, an expert on wind properties at engineering consultancy firm Wintech.

"The downdraught effect is most strong where buildings stand face-on to the prevailing wind, which in London is from the south west."

More rounded buildings, such as London's Gherkin, don't have quite the same downdraught effect and don't encourage an increase in wind speed around them, as the air doesn't accelerate around corners, he adds.

As the air at higher altitudes is colder, it can create chillier micro-climates when downdraught from skyscrapers reaches street level.