helm wind A local name for a type of lee wave that occurs frequently in winter and spring on the western (lee) slope of the Crossfell range in Cumbria, England. Associated with this cold, gusty, north-easterly wind, the helm itself is a thick bank of cloud along the mountain range, together with an outlier of narrow, almost motionless cloud away from the range.

helm wind Local name for a type of lee wave frequent in winter and spring on the western (lee) slope of the Crossfell range in Cumbria, England. Associated with this cold, gusty, north-easterly wind, the helm itself is a thick bank of cloud along the mountain range, together with an outlier of narrow, almost motionless cloud away from the range.