Monday, July 18, 2022

Stay Cool: Urban Surface Heat on Hot Days

 As temperatures heat up this week, and heat warnings hit various cities around the world, consider that surface temperatures might vary slightly from what the weather report indicates. The weather report may be correct, but the surface might be lower or much higher than the atmospheric conditions.

What might make a surface hot during the summer? Asphalt, concrete, and brick absorb—rather than reflect—the sun's heat, causing surface temperatures and air temperatures to rise. This can be worse in areas with reduced vegetation. Trees and plants naturally cool the area due to shading and evapotranspiration. Analysis has shown that dark roof surfaces may reach temperatures of 230°F in summertime!

Here is a visualization of the surface temperatures last year, on September 12, 2021, when the ambient temperature was 82° F. You can see that the different areas of the city vary a lot depending on several factors.

Proximity to water and parks can help a lot to mitigate temperature. Areas with lots of buildings, roads, and surface parking store heat throughout the day and release it at night. 

Lansing maintains a list of public and free cooling centers: if you find yourself in a dangerous situation, here are some locations you can head to.

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