Urban Heat Island

We are all familiar with the fact that cities are generally warmer than the surrounding, more rural areas. We see it referenced most nights in our television weather reports. It is especially significant on nights with clear skies and light winds which favor radiational cooling. This is most significant in the rural areas but in the city, the excess heat absorbed during the day and the local heat sources maintain higher nighttime readings. During the days or nights with strong winds and clouds the differences are minimized due to mixing and the advective cooling of the city by the winds.