This time of year we see a number of flags flying in celebration of the Fourth of July! They are interesting thermally— but only when they are in the sun! While the emissivity of the different colors of the flag is similar in the infrared wavebands we work in, there are significantly different rates of absorption in the ultraviolet, visible and near-infrared. As the full spectrum sunlight is absorbed, much of it is converted to heat and the darker colors end up being warmer. One can find a physics lesson almost anywhere! Enjoy the parade.
Thermally Yours,
John
ASNT NDT Level III #48166
The Snell Group
www.thesnellgroup.com
www.thermalsolutions.org
800-636-9820