Heat on the rooftops
Monday, April 30, 2012 at 08:56AM 
NASA Earth Observatory
NASA Earth Observatory has an image and temperature map of rooftops in a segment of Queens, New York. The temperature on dark roofs "routinely exceed what you might find in the desert.” According to Stuart Gaffin:
Cities have been progressively darkening the landscape for hundreds of years. City roofs are traditionally black because asphalt and tar are waterproof, tough, ductile and were easiest to apply to complex rooftop geometries. But from a climate and urban heat island standpoint, it makes a lot of sense to install bright, white roofs. That's why we say, ‘Bright is the new black.’”
A vegetated roof is even cooler:
Gaffin and colleagues compared the surface temperature of black, white, and “green” (vegetated) roofs and found that black roofs can be up to 30°C (54°F) hotter than a green or white roof. Installing a plant-covered roof is the ultimate technique to combat urban heat because it adds a combination of slight shading and a lot of cooling moisture.
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