What is an Urban Heat Island?

Urban Heat Island

Have you ever felt significant differences in heat between metropolitan areas and their surrounding rural areas? What you’re feeling is the effect known as the “urban heat island.” This occurrence is driven by changes in surface temperatures such as roads and roofs, as well as atmospheric changes in temperature.

Heat islands start to develop as vegetation and other surfaces that easily transfer heat are replaced by surfaces that are solid and don’t allow air or moisture to pass through. During traditional urban development, greenery like trees and grasses are replaced with surfaces like cement and asphalt. As a result, city inhabitants are left with impermeable, dry surfaces that reflect heat rather than absorb it.

Hard, waterproof surfaces like asphalt are heated by the sun and their temperature rises throughout the day. Other sources of heat, such as vehicle exhaust, contribute to the generation of even more atmospheric heat. Physical structures such as skyscrapers contribute to the problem as well. These structures absorb heat and block the free flow of air, thus making it more difficult for these surfaces to cool.

At night, these surfaces gradually cool and release heat into the air, causing a rise in atmospheric temperature at night and keeping the air from cooling as much as it normally would. That starts daytime temperatures off at a higher level before the sun begins heating surfaces again. These changes in temperature are far from subtle. The atmosphere in an urban heat island can be up to nine degrees Fahrenheit hotter than in surrounding rural areas. Additionally, pavement that reaches 100 degrees can quickly bring room temperature water up to 95° Fahrenheit.

Phoenix: Arizona’s Urban Heat Island

Not surprisingly, Phoenix is a textbook example of the urban heat island, with the effect of the heat island reaching as far as 25 miles from Sky Harbor International Airport. According to the Georgia Institute of Technology’s Urban Climate Lab, the pace of warming in Phoenix is happening at an alarming speed – three times that of the earth as a whole, to be more exact. More research from these specialists shows average temperatures in Phoenix rising almost one degree Fahrenheit each decade.

The science behind urban heat islands makes it clear that Phoenix won’t be cooling down anytime soon. If you’re burning up in the Arizona sun, contact Superior Sun Solutions today. We’ve proudly been offering high-quality sun screens and awnings since 1993, and we can’t wait to help you beat the heat.

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