31 August 2014
You’ve probably heard about the urban heat island effect, but I bet you do not realize is how much it affects your weather (and how much it costs you in cooling costs). The folks at Climate Central put out a report this month that breaks down how large the temperature differences are between some cities, and the rural areas surrounding them. The report makes it obvious that we are paying a lot of extra money to cool our homes and businesses, while adding more pollution to the atmosphere in doing so. If you live in Louisville, Kentucky then you have about 23 more days above 90 degrees every year due to the heat re-radiated by the roads and buildings.
Check out the interactive below to see how much warmer cities in your area are:
NOTE: There is an error in the interactive, and the FEWER DAYS ABOVE 90 should read MORE DAYS ABOVE 90.
The extra heat speeds up chemical reactions and causes increased ozone to form as well. In other words,the same vehicle pollution levels in a rural area, will lead to less ozone than in cities because the temperature is cooler there.
If you are in Washington, D.C., you can easily feel the heat island for yourself. I recently rode the metro from downtown, out to New Carrolton station in Maryland, and the temperature drop was at least 6 degrees. The DC heat island is one of the biggest in the U.S., and forecasters like me must take it into account every day. I even factor it into account when making snowfall forecasts and overnight low forecasts in smaller cities.
How do we fix it? Making our cities more green and reflective is one way, but a paper in NATURE last month (July 2014) indicates that the heat island in cities has to do with the fact that cities are aerodynamically smoother than tree covered areas around them, and this reduces convection of the heat to higher levels.