What is an Urban Heat Island and How Does It Affect the Global Water Cycle?
It is estimated by the United Nations that by the year 2025, 60% of the world’s population will live in cities. As cities continue to grow, urban sprawl creates unique problems related to housing, traffic, pollution, and land use. The growth of cities can also impact the weather, climate, and the global water cycle. A close look at the local weather maps on television everyday shows that cities tend to be 1-10 F warmer than the surrounding suburbs and rural areas. The heat-retaining properties of these buildings, roads, and other surfaces (e.g. asphalt, concrete) contribute to the formation of this “urban heat island” effect. Less obvious from these maps, however, is that large cities also may “create” their own weather. Historical ground-based studies and recent satellite-based studies suggests that the urban heat island noticeably impacts summer rainfall over and downwind from major cities such as Atlanta, Dallas, San Antonio, Houston, Tokyo, and Nashville. If you live in certain par
