Over the past thirty years there has been increasing interest in what have been called urban heat islands (UHI),[1] but it is only since 2007 that thought has been given to the rising columns of warm air, or ‘thermal plumes’ that they produce.
[2][3] London’s meteorological aberrations were first studied by Luke Howard, FRS in the 1810s,[4] but the notion that this large warm area would produce a significant urban thermal plume was not seriously proposed until very recently.
[5] Though their velocity is generally less, their very much greater magnitude (diameter) means that urban thermal plumes will have a more significant effect upon the mesometeorology and even continental macrometeorology.
However, there are several reports that shrinking polar ice is due more to changes in ambient wind direction than to increasing environmental temperatures per se.
[7] It has been severally reported that in a stratified atmosphere cross-stream exchange occurs above the planetary boundary layer when there is a vertical motion of significant moment.