UK

UK Weather Forecast Sees Thundersnow Storms Bend Lampposts In Terrifying 'Vortex Shedding'

30/01/2015 09:32 GMT | Updated 30/01/2015 14:00 GMT

No we haven’t laced your coffee with hallucinogenic drugs – these lampposts really are dancing and swaying like daisies in the wind.

The mind-bending sight was filmed by Bob Hill on the M62 between Wakefield and Leeds on Wednesday.

Hill uploaded the video to Facebook where it has been viewed more than one million times in just two days.

vortex shedding

Vortex shedding. On a motorway near you

vortex shedding

The phenomenon is known as “vortex shedding”, a spokesman for the Highways Agency told MailOnline, adding it: “Only happens at certain wind speeds and is a known but fairly rare event.”

Vortex shedding occurs when the wind hits a mechanical system at a specific frequency, causing the system to “excite” and produce a high vibrational load, explains Sparta Engineering.

SEE ALSO:

Windspeeds on Wednesday reached 108mph in some parts of Britain, the Met Office said.

Much of Britain has been lashed with thundersnow storms in recent days – that is normal thunderstorms but with snow rather than rain.

A rare phenomenon, it is caused in the same way thunder and lightning are triggered during the summer, when a pocket of warm air at ground level rises and collides with the colder air above it.

vortex shedding

Britain is being lashed with thundersnow storms

Even though temperatures in the UK are, in places, a little over freezing, the air above it is still significantly cooler. In the summer, this process creates heavy rain showers and lightning storms.

In the cooler winter, the country is pelted with snow instead. The snow contained within the thunderstorm acts to dampen the sound of the thunder and while the thunder from a typical storm might be heard many miles away, the thunder during a thundersnow event will only be heard if a person is within two to three miles of the lightning.

When thundersnow occurs at night the lightning seems brighter - this is because the lightning reflects off the snowflakes.

On Thursday up to 9 inches of snow fell in parts of Britain.

Snow