Blue skies in another waveband

Blue skies in another waveband

Something different, if I may, this the “blue sky” but as seen through a thermal camera that senses otherwise invisible, long-wave infrared wavelengths (8-12 microns). We all know that clear skies, night or day, allow the Earth’s heat to radiate to deep space. This image, even with low spatial resolution, shows the deep sky to be below -22F (calibration may be off!), the sunlite tree in the foreground in the 30s and 40s, and, just above the square in the center (the temperature of which is displayed at -7.6F), is a quarter moon.

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Just enjoy! Not a great photograph but maybe something we can learn from about our invisible world.

Technical Details

Is this a composite: No
Fluke thermal imaging camera that senses 8-12 micron wavelenths.


An interesting scientific display, John.

This is the winner for me, for something really different!! I’d love to know more about this sort of photography and its uses.

Thanks to you both. Again, this is not a great visual image. I no longer have easy access to thermal imaging systems with high spatial resolution and none, except top-secret military systems, are even close to being a good as our common point and shoot cameras. But these cameras see thermal infrared radiation, as opposed to either visible light or the kind of “infrared” (near-infrared) that are made by visual cameras converted with filters. This thermal system can detect differences in temperature as small as .01 F degrees. They are relatively easy to use but understanding what you are seeing often proves a real challenge. In my career of 30 years teaching people all over the world how to interpret images, I realized the key was a basic understanding of simple “kitchen physics” or what we began calling learning to Think Thermally. All objects above absolute zero radiate these infrared wavelengths. We can feel that radiation with our skin but these cameras are much more sensitive than that. The sun warming us, the red coils of a toaster, or even the “heat” given off by snow in January—all radiate this electromagnetic energy. On a more practical level, with “think thermally” skills we could not only see fine temperature differences but also thickness, moisture, subsurface anomalies, and more. Then it became possible to find heating in electrical connections or bearings long before failure. Also inflammation in bodies, defects in composite materials, air leakage, differences in heat transfer, etc. Even with this simple camera in hand, I could walk into any utility substation in the world and in less than an hour typically find issues that would soon result in a million dollars worth of damage or failure. When I first started using them in the in the early 1980s, systems cost $50K or more. Now you can be rudimentary systems that attach to a cell phone for less than $500. Let me know if you have any other specific questions, Diane. And, again, this is a different waveband being detected than most photographers see with the converted cameras seeing “infrared.”