The area has a reputation for cloud and fog – especially the east coast, which experiences a distinctive sea fog known as fret – although the Clean Air Act 1956 and decline of heavy industry have seen sunshine duration increase in urban areas in recent years.
This definition will be used in this article, except when otherwise stated.
Other definitions use historic county boundaries, in which case the North is generally taken to comprise Cumberland, Northumberland, Westmorland, County Durham, Lancashire and Yorkshire, often supplemented by Cheshire, The Isle of Man is occasionally included in definitions of "the North" (for example, by the Survey of English Dialects, Visit Britain and BBC North West), although it is politically and culturally distinct from England.
These averages disguise considerable variation across the region, due chiefly to the upland regions and adjacent seas.
The prevailing winds across the British Isles are westerlies bringing moisture from the Atlantic Ocean; this means that the west coast frequently receives strong winds and heavy rainfall while the east coast lies in a rain shadow behind the Pennines.
Northern England contains much of England's national parkland but also has large areas of urbanisation, including the conurbations of Greater Manchester, Merseyside, Teesside, Tyneside, Wearside, South and West Yorkshire.