Heat Part 2

A fire, with its radiant heat, is a great way to get warm on a cold autumn day.

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Heat is energy, called thermal energy, and is just one type of energy. Other types of energy include, electromagnetic, nuclear, sonic, gravitational, mechanical, chemical, potential, and kinetic energy. All of these are at work in our daily lives and often work together. For instance, when you drive a car, you use electrical energy to start it. Fuel combustion is a chemical energy reaction that converts potential energy to mechanical energy; kinetic energy keeps you moving forward and the result of the chemical reaction is thermal energy out of the tail pipe.

Thinking of heat as energy is helpful when trying to visualize how heat influences our lives outdoors. There are a couple of properties of thermal energy that are important to note. First, everything that exists above absolute zero (zero degrees Kelvin) has thermal energy associated with the motion of the molecules within. The higher the motion of the molecules, the higher the heat. Second, thermal energy always seeks equilibrium and heat transfer occurs from the warmer object to the cooler one. Finally, this transfer of energy isn’t always linear and can be influenced by such things as atmospheric pressure. For instance, water boils at 212 degrees at sea level, but with each ensuing increase of 935 feet in elevation it boils at 1.8 degrees Fahrenheit less. So where I live at around 6,500 feet asl, water boils at 189 degrees F.

When we venture outdoors, we try to influence thermal transfer and the continuous search for thermal balance by the clothes that we wear and by our activities. If it is cold outside, we wear more clothes or more efficient clothes or build a fire. If it is hot, we may wear clothes that protect us from the effects of a hot sun and seek shade or a dip in a pool during the hottest part of the day. Either way, while we may not know it, we are trying to counter or utilize the effects of the three common ways for heat transfer: Conduction, convection, and radiation.

Conductive heat transfer is the process of thermal  energy transfer through a material

without any movement of the material itself.

There must be a temperature gradient, meaning one object is warmer than the other. Metals are great at heat conduction. If a piece of steel has been laying in the sun on a hot summer afternoon and you pick it up, the much hotter metal is going to transfer energy into your hand as it seeks an equilibrium (remember number two above). Hold onto that metal long enough and it will transfer enough heat energy to damage your hand with a burn. The important thing about conduction is that it takes direct contact with the item. Conduction can happen in any state of matter, solid, liquid, or gas, but is most effective in solids where the molecules are densely packed.

Conduction can be a significant source of heat loss from your body. If you sit directly on snow you are in effect trying to heat the ground below you with your body. Handling snow and ice with ungloved hands will quickly rob heat from your hands and ultimately, your core. The key is to always have an insulating layer between you and anything colder than your body.

Radiant heat energy does not require a medium like a block of iron to transfer energy. Radiant heat energy transfers via electromagnetic energy. The block of sun-heated iron emits radiant heat that you can feel when your hand gets close to it. The sun emits radiant heat as does a campfire.

Our bodies are constantly radiating heat away from us. This can readily be seen with infrared detection cameras where our warm bodies glow red against the cooler background. When it is cold, the proper choice of clothing is important in keeping, as long as possible, the heat we generate as warm-blooded animals. Layering to trap air and moisture wicking inner layers are important. And this is where those small silver survival blankets can really make a difference. While they don’t provide insulation, they do reflect back a significant amount of body heat making them worth carrying on any adventure outdoors.

I have used radiant heat in the form of handwarmers for many years. I started with ones that used a chemical reaction to produce the heat (ignited charcoal sticks), then moved on to those utilizing a flameless chemical reaction, and just last year purchased a set that uses electricity to produce heat. But in all cases, unless I hold them tightly in my hand for conduction, they are producing a radiant heat.

Convection heat transfer can strongly influence individual comfort and survival and even life on Earth. More on that next time.

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Help Idaho Wildlife

When we traveled across the state in October 2017, we visited most of the Idaho Department of Fish and Game wildlife management areas. Most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.