Helm Wind

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The Helm Wind is a named wind in Cumbria, England. A north-easterly wind which blows down the south-west slope of the Cross Fell escarpment, it can be so strong that it has been wrongly described as a hurricane. It is the only named wind in the British Isles. It may take its name from the helmet or cap of cloud that forms above Cross Fell, known as the Helm Bar, since a line of clouds over the fells can predict and accompany a Helm.

(It is a local example of the strong winds that can blow down-slope in the lee of mountain barriers, known as foehn winds. This term originally applied to winds in the Alps but is now used for similar winds elsewhere - but there are many local names).

Valuable research into the wind was carried out by Gordon Manley in the 1930s. Manley interpreted the phenomenon in hydrodynamic terms as a "standing wave" and "rotor", a model confirmed in 1939 by glider flights.

Helm Bar over Mallerstang Edge

The Helm Wind in Mallerstang:
The dale at the head of the Eden Valley has its own version of the Helm Wind, which sweeps over Mallerstang Edge and affects especially the central part of the dale. This can be equally fierce and can blow for two days or more, sometimes sounding like an express train.
As is the case for its better known bigger brother, the coming of a Helm Wind is accompanied by the formation of a dense cap of cloud (a "Helm Bar") which, in this case, forms along the high ground on the eastern side of the dale.