As we inevitably move into winter here in Vermont, talk often turns to the weather, and in particular, the temperature. We all live with some unrealistic illusions about temperature. For instance, people can be tricked into thinking they are comfortable simply by adjusting a thermometer to show a slightly higher temperature, and in fact they should. We think nothing of walking around in light clothing on a 55°F day in January, but bundle up in winter coats when the July thermometer shows the same temperature!
Part of the issue is comfort. We tend to filter information about temperature, which is not only quite subjective, but also based on much more than just air temperature. Ambient air temperature is what we typically are referencing when we ask “what is the temperature?” Comfort is dramatically affected by drafts, radiation to nearby warm or cold surfaces, our individual physiology, humidity, and even our beliefs. No wonder it is hard to correlate temperature with comfort!
When we then add thermal imaging into the mix, life gets even more complicated. We are under the illusion that we can simply point this magical imaging device at some target, possible correct for emissivity and background, and display the “correct” temperature.
The truth is a bit more complicated. If we work within the limitations of physics and the tool we are using, we should be able to arrive at the most accurate measurement possible with a certain degree of precision.
Is that “exact?” Wikipedia has an excellent introductory discussion of what is considered a highly complex topic. I recommend it to all readers. We can make accurate measurements even if they may not be exact. Even if we can understand the difference among ourselves, can we explain it if needed, to our customers?
We must be able to both understand what we can and cannot do and be able to communicate the truth clearly to those with whom we work. And even when we understand the limits of what we can do, we must then ask ourselves “what does it mean?” We’ll continue that discussion another time!
I’m certain these and similar issues will become more commonly discussed and argued as more and more people use thermal imagers. Unfortunately, I suspect in many cases both the tools and the tool users will not be well-suited to the task as hand. The New Year would be a great time to promise ourselves that we’ll learn more about what our imaging systems can and cannot do and how we can get the best results possible.
John Snell—The Snell Group, a Fluke Thermal Imaging Blog content partner