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Unusual 'cloud streets' spotted over Oxfordshire and Gloucestershire

Cloud streets over Cirencester Image copyright BBC Weather Watchers / Major Tom

Spectacular cloud formations known as 'cloud streets' have been spotted in southern England.

The long streaks of cloud were seen by BBC Weather Watchers in Oxfordshire and Gloucestershire on Thursday evening.

BBC weather presenter Simon King said the clouds are not uncommon in the UK but these stood out against the fading light of the sky.

"Cloud streets are essentially long rows of cumulus cloud aligned in the sky with the wind direction," he said.

Cloud streets above Tackley in Oxfordshire Image copyright BBC Weather Watchers / Mary McIntyre
Image caption The formation was spotted in the sky above Tackley in Oxfordshire
Cloud streets in Little Rissington, Gloucestershire Image copyright BBC Weather Watchers / Andrew in the Cotswolds
Image caption They were also captured on camera in Little Rissington, Gloucestershire

BBC Weather presenter Simon King explains how 'cloud streets' form

Warm air on the surface rises, cools and condenses into cloud.

In certain situations a warm layer of air in the lower atmosphere, called an inversion, acts as a lid preventing air from rising any further.

This means at the top of the cloud, the cooler air is forced out horizontally where it will then start to sink back to Earth.

In this area, cloud doesn't form, so it is clear. This all sets up a cylindrical circulation which is parallel with the wind, creating the long row of cloud.


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Cloud streets above Oxford Image copyright BBC Weather Watchers / PCGN7
Image caption Clous streets were also seen above Oxford

The phenomenon was spotted in Oxford and Tackley in Oxfordshire, and Little Rissington and Cirencester in Gloucestershire.

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