The clearly defined narrow cloud is believed to be cause by the Helm wind - a result of the geograph of the fells - and was seen by thousands of people as it drifted over Cumbria
Known as Helm Bar, the 'roll cloud' formation stretched across the sky above Carlisle, Cumbria.
Extreme weather conditions which are unique to the highest point of the Pennines created the striking tube-shaped cloud.
The helm bar cloud formation is only said to end when the direction of the wind changes again.
The phenomenon occurs when the helm - a strong, blustery easterly wind that descends the western slope of the Cross Fell Range in Cumbria - creates a rotating roll cloud form
Extreme weather conditions which are unique to the highest point of the Pennines created the striking tube-shaped cloud
Jon Mitchell, ITV Calendar weather reporter, said: 'It is formed down wind at Crossfell, which is the highest point of the Pennines.
'There has to be a strong north-easterly wind for the cloud to form. Air is forced to rise on the eastern Pennines at Crossfell.
'When there are strong winds, the cloud forms a roll that is called a Helm bar. A by-product of the Helm bar is often very gusty winds in the Eden valley.'
The helm wind is unique to Carlisle and can last for days at a time.
The helm bar cloud formation is only said to end when the direction of the wind changes again
Reader Comments
to our Newsletter