The fascinating article on the Urban Heat Island (UHI) of Birmingham in February's Weather has as its stated objective an increased understanding of the local UHI following initial work in the 1980s.
UHIs are the product of the total built-environment when green fields, woods etc. have been replaced by bricks, concrete, tarmac and so on with different thermal properties, which are well known.
Most cities are approximately nucleated, but where they are dispersed the whole urban area should be studied. It would be foolish to study London's Heat Island by only studying the western half or the eastern half.
It has to be realized that Birmingham is only one half of a built environment. Although the city has borders to the north, east and south with open agricultural land, to the west and northwest it is contiguous with the Black Coun--try – birthplace of the Industrial -Revolu-tion – consisting of the Metropolitan boroughs of Wolverhampton, Walsall, Sandwell, and Dudley (with a combined population about the same as that of Birmingham, around one million).
The densely-built environment of Sand-well passes seamlessly into Birmingham – but this study does not.
I would have thought that it is necessary to study the whole of the West Midland urban area to really thoroughly understand the UHI.