What is the urban effect on sunshine?
This is one aspect of the region’s climate that has dramatically changed over the late 19th and 20th centuries. At the height of the Industrial Revolution in the latter half of the 19th century, vast amounts of smoke and soot were emitted into the atmosphere in London. This led to the absorption or blocking of a remarkable proportion of the incoming radiation from the sunshine and hence sunshine amounts were curtailed. It is difficult to believe today how profound this effect was and how quickly it has changed. In the 1880s, it was estimated that London was ‘losing’ up to 80% of its winter sunshine. In December 1890 no sunshine was recorded at Westminster. As recently as 1921-50, central London averaged only 50% of the winter sunshine as surrounding rural areas. The effect was concentrated in winter because of the increased emission of smoke and soot associated with the greater use of coal burning to heat houses and offices and also because of the low angle of the sun. The situation is
