Calming time-lapse footage captured in northern England showed a rare swirling cloud formation, a phenomenon called the "Foehn effect".

The cloud formations were filmed yesterday (April 9) in the North Pennines area over Wild Boar Fell, a mountain in the Yorkshire Dales National Park.

According to this filmer, the clouds move around like this when: "Cold strong east winds blow across the Pennine hills causing the cold air to go upwards and mix with much warmer air from the west "

Time-lapse footage captured in the North Pennines over Wild Boar Fell of an unusual swirling cloud formation. This phenomenon is known as the Foehn effect. This happens when cold strong east winds blow across the Pennine hills causing the cold air to go upwards and mix with much warmer air from the west and forming these beautiful clouds.

Here in Cumbria, the strong east winds are called helm winds and the swirling cloud affect helm clouds or a helm bar.