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IR Odds & Ends

I seem to have accumulated a short list of items each of which is too small to be a week’s posting by themselves, but all of which I wanted to share with you—thus the title of this week’s posting!

First: A follow-up to let you know that the ice on Joe’s Pond here in Vermont finally did melt!  The ice actually went out on April 27 at 10:17 pm. The earliest it has ever gone out was last year, 2010, when it went out on April 5, and the latest it has ever gone out was in 1992 on May 6. The record snowfall we had this winter (snow reflects the heat of full spectrum sunshine) along with a cold spring proved the difference for the slow melting. Now the question is, when can I jump in the pond—an issue mainly of capacitance but also bravery!

Second: Below are two books I’d like to recommend to you for your summer reading, both remarkably well-written to provide excellent ways to round out your thermal education:

Matter of Degrees: What Temperature Reveals about the Past and Future of Our Species, Planet, and Universe, by Gino Segre (out of print but still available used)

Summer World: A Season of Bounty, by Bernd Heinrich

Many creatures have the ability to regulate their body temperature. Ravens do this by controlling blood flow to their feet and heat. I took this image, part of a project I did with noted author and scientist, Bernd Heinrich, which shows the bird ridding itself of heat after a period of intense flight. After a few minutes, the feet cooled to the point where they blended in with the ambient surroundings!

Both books deal extensively with various, mostly applied, aspects of temperature in ways that include the human experience rather than just physics. The real bonus, however, is that both books are so finely written that they are a pleasure to read. While your friends and family are reading the latest pulp on the Times Bestseller List, you’ll be reading something that will really entertain—and inform! Although I’ve highlighted these two books, I’d also recommend any of the other books written by either author.

Third: Here is a collection of thermal thoughts from the garden.

Thought #1: We joke that Vermont has two seasons, 9 months of winter and 3 months of damned poor sleddin’. We’ve reached that point in the year where we trade the sleds in for our garden forks. A garden to be proud of depends both on sunlight and soil that has warmed up to an optimum temperature. Obviously this changes from season to season and, yes, conditions can get too warm as summer progresses. The sun’s radiation warms only the surface of the soil, but it is conductive heat transfer to the sub-surface soil temperature that is really important both for seed germination and plant growth. Many websites now update changes in average soil temperatures, but in the end, we have to pay attention to local conditions or even the microclimate of our particular “pea patch.”

Thought #2: As the sun lifts higher in the sky and stays up longer (here in the Northern Hemisphere), we see the affects of solar warming in many ways. No sooner do plants leaf out, the bugs arrive. Along with the bugs, the insect eating birds and bats creep out. Bees, too, are thermal creatures, needing to warm up their flight muscles before foraging for nectar—and the hive is a carefully managed thermal environment. When it is cold,  the bees cluster together to reduce heat loss and, when it is hot, they set up an elaborate forced convection system to move air through the hive using the power of the wings of hundreds or thousands of worker bees!

The warmer area on this bee box correlates with the location of the hive inside. Staying together in cooler weather helps the bees reduce heat transfer and maintain a temperature required for survival.

Thought #3: If you want to be a thermal pioneer, there is a great deal to be done looking at plants using thermal imagery. We know that a healthy plant, compared to one that is stressed, will be cooler because evapotranspiration is directly associated with plant health. Some work has been done to document “pre-wilt” conditions in crops such as grapes and citrus. But before we can visibly see a plant wilt and know we should provide water to it, there is often a subtle change in temperature. By the time many plants actually wilt, a great deal of damage has already been done.

The beads of water this Lady’s Mantle leaf have exuded, a process called guttation, can easily be seen due to the cooling affect of the evaporation of the water.

Thought #4: Another interesting phenomenon in plants is “guttation”—or, the exuding of water from cells along the edge of the leaf during the night. If you look, it is common to see this on the leaves of various species, such as strawberries, tomatoes, Lady’s Mantle or Hostas, especially early in the morning after a clear night.

Thought #5: Like many gardeners, I have a compost pile. Unlike many gardeners who

The interior temperature of a well-built compost pile often exceeds 160oF (80oC) even if the outside of the pile is much cooler.

just toss their “kitchen wastes” onto a frozen pile, however, I collect mine in sheetrock buckets all winter and store them in an unheated garage. Layered with soil and kept cool, they don’t decay much and certainly don’t smell. Why do this? Because in the spring, I can use the buckets (12 this year) to build a “hot pile” that breaks down quickly into wonderful “black gold.” A well-built compost pile can reach internal temperatures of 160oF (80oC) or greater in less than a week.

Thought #6: Along similar lines, many kinds of organic materials that are piled (coal, hops, hay, etc.) generate heat, often to the point of spontaneously igniting. Thermal imaging is widely used to monitor these situations. Like my compost pile, however, the surface we see in the thermal image will be much cooler than the interior temperature.

Wherever you are this week (north of the equator at least), I hope you are enjoying Spring. It is a wonderful time to Think Thermally!

Thinking Thermally,

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

3 comments to IR Odds & Ends

  • Michael Stuart


    Great Post! I would also like to chime in and say that “A Matter of Degrees” was one of the most enjoyable books that I have read in at least ten years. It really has a little something for everyone in it… all revolving around “temperature”. I highly recommend it to anyone who is looking for something a little different and something that will challenge your perception of the world and all that is around us!

  • Very Large compost operations put out VOC and Methane. Some of these constituents are odiforous. I have seen examples of thermo images used for detecting VOC leaks from refinery piping systems. Could IR thermo imaging be used for detecting which direction composting plumes move horizontally, or vertically, for at least a 100 yards?

    v/r claude
    Air Pollution Engineer

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