![]() ![]() You can have a room with an air temperature of a comfortable 72° that can still feel hot or cold to an occupant based on the temperature of the surfaces around them. ![]() The real-world effect of thermal radiation on heat load and human comfort is huge. This is why these weird “space blankets” can keep a person warm by simply reflecting back their own thermal radiation. Thermal radiation can be “reflected” in the same way as visible light. The net thermal (heat) effect on our body is based on whether the average surface temperatures we are exposed to are higher or lower than our body temperature. In the case of the human body, we are putting off radiant heat to everything around us and picking up radiant heat from all of those same objects. That is because EVERYTHING that is above absolute zero puts off thermal radiation in the form of electromagnetic radiation everything in our world is above absolute zero (-460☏), so everything emits radiant heat. This image could have been taken in complete darkness, yet it displays the thermal radiation. Take a look at this photo above taken using a Testo thermal imaging camera. While this is partly true, the VISIBLE light spectrum is only a small part of the story. Many have taught that radiant heating (thermal radiation) happens when one body of matter is exposed to a light source such as the sun or a fire. That happens because the flame is heating your face through THERMAL RADIATION, not by heating the air in between. The minute you put your hands up and shield your face from the light of the flame, your face cools off almost immediately. If you've ever sat close to a bonfire on a really cold night, you may have noticed that your face starts to get really warm. ![]()
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