Manhattan

Air Quality Action Day? Worry Not, NYers!

Michael Animation, Data & Graphics, Photo, Video July 22, 2017

If you have never heard of an air quality action day, you are most likely a perfectly typical resident in the U.S. who is also lucky, the latter of which you may have been taking for granted. Because a hazy day like July 20, 2017 in Manhattan almost never happens. (Hazy is not the same as “foggy.”)

Manhattan skyline July 20 vs 21, 2017 seen from Queens

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Heat Island Effect Thermal Imaged in NYC

Michael Data & Graphics, Photo July 17, 2016

热成像拍摄纽约热岛效应及雾霾的增温效果

The Statue of Liberty trapped in smog-generated heat

50F = 10C, 68F = 20C, 86F = 30C

纽约的这点雾霾(以上右图)对于见过世面的国人来说最多也就是点雾吧(这里看到的所谓的霾应该大多是臭氧)。即使就这点雾霾,也令地表空气和地面温度陡然升高,比海水高出近20华氏度,专家说,这些颗粒物和水汽会散发红外波段的“长波热辐射”,地面在阳光和这些辐射的共同作用下,温度就比周围环境高出许多。幸好雾霾在北京的夏天不是爆发季。拍摄者是 Nickolay Lamm,是几年前的一个7月用热成像相机在纽约拍摄的。

The water remains relatively cool (blue) all day while the Statue of Liberty warms up when exposed to the sun (red). A haze layer exits near the ground, and the particles and droplets in this layer emit “longwave thermal radiation” in the far infrared portion of the spectrum. The haze closest to the ground is relatively warm (red, orange), while the temperature decreases with increasing altitude (yellow to green to blue). The ground is heated both by sunlight and the longwave radiation emitted by the atmosphere. Haze layers over urban areas increase the longwave heating, especially overnight, and promote warmer temperatures.

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