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Teaser Infrared Image - The Answer

Well, we had one guess that was pretty spot-on–good job Dan!

Infrared Image

Visible Light Image

This is a close-up infrared image of the parapet of a rooftop conglomerate stone wall.  There are several different emissivities represented here, and with the cool sky as a reflected background, this becomes apparent.

4 comments to Teaser Infrared Image – The Answer

  • Dan Laughbon

    I could not think of the word conglomerate,the only thing I could come up with is gravel!

  • Fun! Thanks. One of the first “assignments” I ever had in learning to Think Thermally, though we’d not yet invented the term, was from a brilliant solar pioneer (Steve Baer, Zomeworks) who gave us all dial thermometers and sent us out to measure the temperatures of mudpuddles of various sizes. Sounds simple but involves nearly all aspects of thermodynamics! I wonder if the differences in temperature in the gravel are not due, in part, the the differing sizes of the aggregate, cooling at different rates? You suggest it is reflection, but I wonder… . What time was it and what were the solar/sky conditions before and during?

  • Michael Stuart

    Good points, John. The image was taken in the late afternoon. Sky conditions had been overcast all day long. It was relatively cool as well. The previous three days and nights were very similar. The span on this image was also set VERY tight. Image was taken at about a 45 degree angle as well. No significant solar loading had occurred for a while, but I suppose that some still does happen even in very cloudy weather. It is also possible that heat transfer from somewhere down below (or inside) the wall could have contributed to what was observed as well, but it is not likely to be a major contributor due to where the parapet was located.

  • Dan Laughbon

    Thanks for the Info. and experiances, I could not get back to this blog until today ( Tue. 1-18-11. ) to read your informative comments.( of course they always are. ) Thanks again.

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