"4" Ways Mother Nature Can Show You The Meaning Of Hot
In case you didn’t notice the image, there are three ladies sunbathing at a the beach, oh and a skinny guy too. Funny thing I picked this image because only latter on did I notice the logical parallel with this text. Write me if you know what I m talking…(sorry for any typo, just wrote it with no time to proof read yet)
What Discipline Studies Hot Or Cold?
Hint, not Tinder, Grinder or POF…Let me disappoint you yet a little further, the discipline that studies everything about true Hot & Cold is called Thermodynamics, or, “movement of temperatures”. Well, that is in fact a rather macroish perspective of the discipline and purists will probably frown at it’s inaccuracy. At its core, Thermodynamics is concerned with the statistical energy of molecules and atoms. Temperature and heat are consequences of those states that.
In fact, thermodynamics is so “atomistic” that it was through one of it’s laws (Planck’s Law) that Einstein ended up postulating the Photo-electric effect. Today, the effect is super hyped with solar cells, renewables and green tech and changing the face of the earth.
The “4” Natural Ways You Can Feel “Hot & Cold”
A person can’t feel absolute temperatures, only temperature differentials, or heat flows.
When you grab a cold beer can from inside your freezer, you perceive the can cold, because the temperature difference of your body (~ 37C) and the can (~ 5C), has the nerve cells in your hands to shoot an electric signal to your brain saying “it’s cool”. Here, you experienced Conduction Heat.
When you flame-heat the air in an air-balloon and you start rising in the skyes. That is because any gas - an liquid - tends to naturally move from a high temperature zone to a low temperature zone. That current of air can be capture by the interior of a balloon to create a force and lift you away…Here, you experienced Convection Heat.
When you tan comfortably in a sandy beach under a hot clean sun, you are felling the “sun’s” energy in your body. But, your are not touching the sun directly, and there is certainly no air stream from the sun to your body. So it must be a type of energy that can travel through vacuum, from the sun and reach your tanning self. Here, you experienced Radiant Heat.
Conduction Heat - “The Beer Can”
In the first example of the beer can, we say that you felt the temperature difference through heat conduction. Heat conduction is the most prevalent way of two physically contacting solid bodies to transmit thermal energy from one to the other. The law is governed by the so called Fourier Law of Conduction.
Convection Heat - “Hot Air Balloon”
In the second example, the hot balloon rises because of what is commonly referred to as convection currents. These convection currents occur in liquid state or gas state medium, and, from a higher energy zone to a lower energy zone. In solids this doesnt take place, because solid body molecules are not free to move around. Thermodynamic laws are always fair, always look for evenness…The governing laws are the Laws of Convection.
Radiant Heat - “Sunbathing”
That amazing heat you feel when tanning up in a summer day is called radiant heat. It’s called like this because it is emitted from the sun and propagated through electromagnetic radiation, or light. Yeah light, in all possible forms UV, IR, NIR, VIS. When you get under your beach umbrella, that radiation stops hitting your body and it instantly feels “cooler”. But, it is not just the sun that emits radiant heat away. You know what else emits Radiant Heat? You! your cat, the flowers in your front porch. In fact, everything in this universe does emit. (given an absolute temperature > 0K, which can’t be naturally reached). Plank’s Black Body Radiation law is the most widely used to describe Radiant Heat.
Bonus - Psychological Heat
Ok, this notion isn’t exactly what you’d call scientific or peer reviewed. It is nonetheless a helpful way to distinguish non-thermodynamic feelings of heat.
There are quite a few examples. Say for instance, when you eat a Jalapeno pizza at Domino’s, you’ll experience for sure another brutal yet delicious type of heat. Spicy heat! It’s not really heat, but, rather, a chemical signal fed to your brain, “camouflaged” in a feeling of heat.
Interesting enough is, spicy heat does find its natural counterpart in nature too, a “fictional cold”…Mint for instance, rub it in your skin you’ll feel a similar sensation to cold.
By the way cold, how to say this, it’s not a thing. It’s just a feeling of a temperature difference, where the person feeling it is at a higher temperature then that of what or who is sensed as cold…
Why Is This Important?
When you know and understand which heat streams are present in a fire and how they propagate to you, chances are you’ll take better calls at avoiding the most dangerous heat trajectories. Any fire, be it wildfire, domestic, car, etc, has a mix of the 3 thermodynamic heat exchange phenomena from above.
What makes fires so complex and also interesting is the conditions they take place which make each fire pretty unique.
Next step is, understanding how they work in each type of fire. For that move on the this reading: This Crash Course On Wildfire Thermodynamics Can Save Your Life