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Getting Thermal with Snow!

“Frost audits” (whether snow, frost or dew) can help us understand what is happening with heat transfer on a roof or wall. In this case, there appears to be an area along the eave where excessive heat loss is occurring, either due to air leakage or misplaced insulation.

With our Thanksgiving turkeys under our belt (so to speak), we can now turn our thoughts toward winter and, for many, snow. Although as I write this I am in North Carolina with family and there is no snow in sight, there has already been plenty back home in Vermont. The mountaintops are covered, the upper ski trails are well used, and we’ve even had enough snow down in the valleys to conduct our first “snow audits”. While these are not complete audits, they often mimic a thermal image precisely and can yield useful information about heat loss. The patterns of melting snow, whether on a roof or anywhere else, provide a great example of something we can be Thinking Thermallyabout!

As is the case with all weather, there is a lot more to understand about snow than how to navigate icy roads or how to shovel the stuff out of your driveway. One thing to consider in particular is the transfer of energy during water’s state change from gas to liquid to solid. The way that water vapor forms the snow crystal around a nucleus of dust is complex, and the fact that it can happen countless times in a single storm is just incredible—but every time it happens, energy is released.

To see how much energy is involved in this process, let’s look at this slide from our Level I course that shows the basic relationships among temperature, energy, latent energy and the three states of water.  The graph shows us that as a pound of water vapor condenses into a liquid, it releases 970 Btu of energy (a wooden match burned completely yields approximately 1 Btu!) and as that same pound of water freezes, another 143 Btu of energy is released. This happens regardless of the actual temperature at which the state changes occur. It is no wonder that the inside of a cloud is a dynamic and energetic environment! In the end, what we know is that snow comes out of the bottom (of the cloud) and we get to watch it fall from the sky.

By the way, snow, while highly reflective in the visible spectrum, is “black” in the longwave spectrum with an emissivity in excess of 0.95. Poke a hole in a snow bank and you’ll find it not only looks darker to your eyes, but also begins to melt when the sun shines on it—now that is a fascinating thermal phenomenon to consider!

To learn more about snow and to see some remarkable microphotographs (left), check out Ken Libbrect’s amazing website at http://www.its.caltech.edu/~atomic/snowcrystals/. Ken has written some great books and even offers free snowflake “wallpaper” for your computer! If you live near snow, I hope you enjoy learning from it, and then, among other things, applying what you’ve learned to being a better thermographer.

Thinking Thermally,

John Snell—The Snell Group, a Fluke Thermal Imaging Blog content partner

4 comments to Getting Thermal with Snow!

  • joanne eng

    i am interested in your product for termite inspection for wood damage. Is the productr suitable. What ia the cost?

  • Michael Stuart

    Fluke does make some thermal imagers which can be sensitive enough to detect damage created by termites and carpeter ants. However, as with any thermal imager, the user understands the proper techniquues for using infrared technology for this purpose. TiR32 would be the best model, in my opinion… but other models may also be sufficent depending upon the situation.

    You will need to speak with someone in the inside sales department for details on pricing and availability in your area.

  • Fluke Thermography

    Thanks, Michael. You can find the contact information, as well as a product description for the TiR32, below!

    1-800-760-4523
    thermography@fluke.com
    TiR32

  • You make blogging look like a walk in the park! I’ve been trying to blog daily but I just cant find writing material.. you’re an inspiration to me and i’m sure many others!