If your home is located in a densely populated city or near a lot of manufacturing facilities, it may be in what is known as an “urban heat island”.
These areas have been identified as being significantly warmer due to human activity than the surrounding less populated, rural areas. Generally, the temperature difference is more noticeable at night than it is during the day. It’s also more significant in the summer and winter.
How UHIs Develop
Scientists believe urban heat islands occur when heat produced by factories and by the sun being absorbed by home roofing is absorbed into the ground and storied as short-wave radiation. As areas become more crowded and busier, they tend to increase in average temperature.
The result is that these areas downwind of urban heat islands get more rainfall. Growing seasons also can be extended. Plus, there tend to be fewer weak tornadoes.
But UHIs also decrease air quality due to the increased production of ozone, letting more harmful ultraviolet rays pass through the atmosphere and increasing the risk for skin cancer.
Water quality also be negatively effected because warmer water flowing into streams and rivers can put more stress on natural ecosystems.
How to Prevent Urban Heat Islands
Some cities — such as Salt Lake City, Chicago and New York City –have tried to reduce the effects of UHIs by taking steps to cool down their climates through the use of such techniques as white roofs, green roofs, and by planting more trees within the city limits.
White roofs are when you paint roofing white in order to reduce the absorption of the sun’s heat. White roofing increase solar reflectance and reduce heat buildup.
Green roofs are another way to decrease the effects of UHIs. This consists of planting vegetation on roofing, such as trees or a garden. Plants absorb the heat and convert it into clean air through photosynthesis.
As our climate gets warmer, these and other strategies will become more common in the near future.