'Mini tornado' sweeps through Norfolk pig farm as heatwave continues

The 'dust devil' filmed in Norfolk.

A small twister - or 'dust devil' as it is known - was spotted moving across a pig farm in Norfolk as temperatures reached high levels for another day.

The unusual weather phenomenon was captured by an ITV Sport camera operator who had been filming the British Touring Car Championships at the Snetterton racing circuit.

A dust devil is a small column of rotating air that forms due to temperature changes with rapidly heating air above sun-warmed earth or pavement.

They can form on clear days and usually only travel a short distance before dissipating. They form from the ground upward unlike tornadoes which usually develop downwards from the base of a thunderstorm cloud. Dust devils are much less destructive than tornadoes.

Meteorologist Aisling Creevey said: "This is impressive, but they are harmless.

"This well formed dust devil is caused by rising air that turns into its own self sustaining vortex that is very short lived."

The ITV News Anglia weather presenter said it was "not really surprising" to see this type of weather phenomenon at the moment with record breaking warm and dry weather throughout the summer.

"The normal moisture in the top layers of the soil to prevent this from happening are not currently there and so the top soil is incredibly dry," she added.

There have been reports of similar dust devils appearing over the past few months as a direct result of the hot and dry conditions.