For those of us who live along or very near the east coast, there have been a number of strong windstorms that have occurred. Micro-bursts are a fairly common name for them. One of the strongest that occurred was named a Derecho (4). It came without warning and cut through much of the east coast. Those who believe that climate change is truly upon us, and even those that don’t believe it, can appreciate the magnitude of what happened near the end of June 2012 causing massive power losses all along the general east coast region. The question of why this is happening now has likely crossed many minds and the answers may be more common knowledge than people may think.
If you have ever worn a black or dark color piece of clothing on a hot summer day, you know very well that it makes you hotter than if you had worn something lighter in color. Well as it turns out, cities are largely paved with a dark color substance known as asphalt. Many building roofs are also colored a dark color. Well, just like when your shirt or pants make you hotter in the summer, so too does the pavement. The temperature difference between a city, with around one million people in it, and nearby natural surroundings can be 1.8 to 5.4 degrees Fahrenheit on average (1). In the evenings, this difference in air temperature can be as large as 22 degrees Fahrenheit (1). Whats more, the pavement largely doesn’t allow moisture in the air to be absorbed as is the case with natural soil so run off is created which can pollute a city’s water supply.
Anyone who has taken a cold soda from the fridge on a warm day knows that the can will tend to “sweat.” This is what happens when the moisture in the air comes in contact with a cooler surface which in this case is the soda can (3). The natural ground, with plants and all, is usually cooler than the hot summer air. As such, as is the case with dew formation, the water vapor in the air can form on the ground and the ground can soak it up (3). This allows for less overall energy to be present in the air as water is a very potent heat sink. It also means that the air of the environment is kept relatively cool in comparison to a city. In cities, the dark pavement actually serves to make the air hotter and hotter air can hold more moisture. The surface of traditional paved surfaces can reach summertime high temperatures of between 120 and 150 degrees Fahrenheit (5). It actually helps to drive more energy into the air and with more energy in the air, there is a higher chance for abnormal weather patterns to occur.
With all of these problems, there are some simple solutions that can be employed. A simple way to deal with the effect of dark colors absorbing more heat, or the heat island effect, is to do what anyone would do if the problem were with clothing; wear a lighter color. Likewise, when repaving roadways or choosing a new roofing material, make sure that it is a light color so that the energy is reflected as visible light instead of being converted into heat. There is also the need to preserve, or even erect green spaces as this helps to get the moisture back into the absorbent soil, aid in reducing city temperatures as well as increasing the aesthetic beauty of the city itself (2). Since the green spaces help to better control run off by allowing water to go into the soil, surface water sources used for drinking water are able to be kept cleaner as well as potentially helping to replenish groundwater sources. The combination of using pavements that generate less heat, green roofs, and vegetation can lessen the overall heat trapped by a city and can serve to reduce its overall energy needs such as for cooling of buildings (3).
The numbers in parentheses in the text correspond to the reference numbers below.