According to the United Nations, more than half of all people on Earth currently live in cities, where summertime heat can seriously impact human health. Urban areas can be as much as 7°F (4°C) warmer than surrounding rural areas because city surfaces absorb more of the sun’s heat during the day and emit that heat back into the air at night. Pavement and impervious surfaces make cities hotter. Plants and pervious surfaces make cities cooler through water retention and evaporation. For more information, visit http://climatebits.org
Land surface temperatures vary with the sky, the wind, the land surface, its albedo and the season due to the sun’s angle.
Increasing urbanization – human development of natural areas – can be seen from space by our lights at night.
A map of summertime temperature differences between urban and rural areas shows a striking similarity to the lights at night map. Significantly warmer areas include places such as New York City, London, Tokyo, São Paulo.
Cities can mitigate urban heat island effects by using more pervious surfaces, vegetated and reflective roofs and planting trees.