Artist and web researcher Nickolay Lamm, who previously visualized the extent of wealth inequality in the neighborhoods of Manhattan with a series of 3D maps, is back with a new series of maps this week, inspired by the question: why are cities so much hotter than surrounding areas? To find out, he brought a thermal imaging camera to NYC to see the effect in action—because this is exactly the kind of idea that pops into your brain when it's 95 degrees in Manhattan and your soul is dripping through a sewer grate.

Lamm found an answer to his question: the "urban heat island effect." That's what happens when every surface is paved with heat-absorbing asphalt and concrete. Not helping things here are a lack of plants and trees to cool the air, as well all the heat generated by our electronic billboards, TVs, and buildings.

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Check out the full analysis of various spots in Manhattan here, with commentary by heat island expert John E. Frederick from the University of Chicago.

[h/t Fast Company]