I learned recently on The Weather Channel that people can change the weather (cue evil villain laughter). No, it’s not what you’re thinking. It refers to a phenomenon called the Urban Heat Island effect and it occurs, you guessed it, in urban settings.
Where people have laid down tons and tons of concrete, it’s not surprising to see some environmental effects, but change the weather? Really?
Absolutely. All that non-reflective concrete absorbs the sun’s radiation and reflects it as heat, whereas, a grassy meadow or forested land will absorb the radiation without reflecting it. In urban areas, this causes a bubble of heat (hence the name Urban Heat Island) right over the city. The temperature in outlying areas can be as much as 15 degrees Fahrenheit cooler, especially at night when all the heat soaked up by the concrete during the day is still radiating out.
But the heat isn’t the only weather change caused by urbanization. Areas downwind of cities can see twice as much rain as the city itself. This happens because the air in the city is warmer and can therefore hold more moisture, plus more pollutants from the city cause more nuclei within the air for moisture to condense around. When this warm air moves out and hits the cooler air downwind, it increases the relative humidity of the cloud, also increasing its ability to produce precipitation. I may have lived in Iowa too long, but the first thing I thought of is that I hope some smart farmers out there have taken advantage of this effect by planting crops downwind to capitalize on the rainfall.
Since half the world’s population live in large cities, the Urban Heat Island effect can be a serious thing. Heat kills more people than any other weather related event. But some cities are taking steps to reduce the effect by putting in more parks, special roofs that won’t absorb the sun, and even putting parks on the roofs.
Should more cities be taking steps to reduce the Urban Heat Island effect? I lean that direction because I think God gave us this planet and we have responsibility to care for it. But many people think this isn’t a big deal. What do you think?
Photo Credit: <a href=”http://www.flickr.com/photos/29941355@N04/4303224783″>Denver Skyline at Blue Hour</a> via <a href=”http://photopin.com”>photopin</a> <a href=”https://creativecommons.org/licenses/by/2.0/”>(license)</a>