By Fred Seitz
I think the headline of this February column accurately reflects much of our local weather this winter. However, I have seen a few folks walking around in shorts and T-shirts when my wife and I were bundled in multiple layers — and even my mutt was walking quickly, straining to get back to our warm house. Just as we humans may experience the same temperature in a variety of ways, we use quite a variety of terms to describe the temperature, and in ways that are sometimes confusing.
Every morning I read the temperature on my thermometer and assess what kind of jacket or other protective garb to wear — I’m hardly alone in this habit. But what, exactly, am I reading, and how? Most thermometers show the ambient air temperature, of course. Outdoor thermometers can be liquid, dial or digital. Liquid thermometers used to use mercury; now, for safety reasons, they use nontoxic alcohol. Dial thermometers use a bimetal spring, one made of two different metals that expand or contract at different temperatures and are welded together. Digital thermometers are frequently multifunctional and may also measure humidity, barometric pressure and wind speed. Plunging the thermometer in ice water is a good way of assessing its accuracy — how close is it to 32 degrees F?
Where you place a thermometer can influence readings — sun and shade are factors. Years ago, when I attended some National Oceanic and Atmospheric Administration weather watcher classes, I learned that thermometers measure most accurately if they’re in the shade.
As we read a thermometer, we may notice how much the trees are moving in the wind, too, and wonder about the wind chill factor. We might even wonder about the wind chill temperature, which may sound far more ominous than our humble thermometer’s initial reading.
The practice of using wind chill temperatures was developed, in part, to help folks avoid frostbite, which is indeed painful and can damage limbs and exposed skin. The term “wind chill” originated with two Antarctica scientists, who undoubtedly had some chillier experiences than most Hyattsvillians will ever have. Multiplying the wind speed by 0.7 and subtracting that value from the ambient temperature will give you the approximate wind chill temperature.
And then we have the “feels like” temperature (which is sometimes referred to as the apparent temperature or the Universal Thermal Climate Index). This term factors in another important variable: water. From personal experience, I can attest to the chilling impact of water — think that dash through rain, a slip into creek water, or the frigid shock of falling through broken ice on a pond. And when you’re wet, wind can make your cold body a whole lot colder as it blows your body heat away. Indeed, add wind to the equation and you can quickly go from frostbite to hypothermia, which is a potential killer. (If you do fall into cold water, don’t drop into a hot tub, but try to bundle in a blanket and gently dry yourself.)
Even as we have various ways to measure temperatures, perhaps the most important element is our individual experience of weather. And our individual experiences are affected by many things; body mass, circulation, and how we dress all play a role. And more idiosyncratic factors can factor in, too; you may have fond memories of walking in the rain, or that time your boots were filled with muddy water could prompt you to simply stay inside.
I’ve got to hand it to those little birds and squirrels I see wandering around on days I experience as bitterly cold. I somewhat relate to the turtles who cleverly burrow themselves in mud to endure the cooler times — although I’m not planning to take a mud bath anytime soon. I can also relate to bats and bears, in that I sometimes want to hibernate through as much of winter as I can. And I envy those birds and humans who migrate to points south to avoid a cold, bleak winter.
I wish I could chill out during this time of year, but I’m more focused on figuring out the realest-feel temperature I can (and keeping the chill out). Maybe I’ll just put on another layer or two before I venture out again.