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11-02-2012, 11:18   #1
Aseth
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Body tempretaure vs outside temperature

This one has been bugging me for a while:
human body temperature is 36.6 so why do we feel hot when it's 36 outside?
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11-02-2012, 16:35   #2
krd
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Because, the way the body works, it's constantly generating heat through chemical reactions, and stuff.

So it feels comfortable when we're constantly cooling.

If your body temp is 36 degrees, and the outside temp is 36 degrees, you're not going to cool. You'll be uncomfortably hot. You could even die from heat exhaustion.
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13-02-2012, 06:10   #3
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To stay at around 36 degrees the human body needs to constantly dump heat into the surrounding environment. We are constantly generating heat as krd points out through chemical reactions and mechanical movement. If the surrounding environment is either too hot or too cold then you either can't lose it fast enough to stay near 36 degrees or lose too much heat to do the same.

This interestingly is where the concept of wind chill comes from. Wind chill makes no difference to a piece of metal say other than causing it to reach equilibrium with the environmental temperature faster. With the human body though it can cause the outside temperature to appear to be many degrees lower than it actually is by increasing the rate at which heat is lost by the body. This is why a sea breeze is so refreshing on a very hot day and why strong winds can make a wintry day seem much, much colder than it actually is.
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13-02-2012, 20:42   #4
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Humidity is also a major factor.

36 degrees AND high humidity means your perspiration doesn't evaporate and so it doesn't cool you.

36 degrees and dry means that perspiration will evaporate, cooling you. But it will also dehydrate you. This is one of the reasons why people who live in deserts cover up.



As an aside humans aren't that good at detecting temperatures, just whether they need to be warmer or cooler. Get three basins of water. One hand hot, and one with ice water in it and put a hand in each for a few minutes. Then close your eyes and put both hands into the third basin at room temperature. One hand will feel the water as cool and the other as warm.
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14-02-2012, 00:47   #5
krd
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Humidity is also a major factor.

36 degrees AND high humidity means your perspiration doesn't evaporate and so it doesn't cool you.
Yes.....but it doesn't stop it from condensing and just rolling off.

And one reason humans have been so successful is their ability to adjust to different environments. People who live in equatorial regions are not dropping dead from heat exhaustion. Drop the same person in Northern Europe for the winter - they'll have a much worse experience than the Northern Europeans who experience it all the time.

Humans become acclimatised relatively easily. Other organisms usually die if you change their environmental temperature just by a few degrees. Humans, cockroaches, and bacteria, are not so bothered. Malaria carrying mosquitoes are.
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14-02-2012, 01:26   #6
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Humans become acclimatised relatively easily. Other organisms usually die if you change their environmental temperature just by a few degrees. Humans, cockroaches, and bacteria, are not so bothered. Malaria carrying mosquitoes are.
You don't see that many cockroaches in Ireland, it's too cold

bacteria covers a multitude of organisms with many differing tolerances to everything

water bears are the animals that probably have the highest tolerance of environmental conditions
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14-02-2012, 10:11   #7
krd
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You don't see that many cockroaches in Ireland, it's too cold
We've been lucky, that there hasn't been a cockroach that likes our climate.

We've been lucky as far as creepy crawlies and insects go. I knew two Germans who moved to Ireland a few years ago - in the winter. They were panicking about the house they were living in - it had no insect nets on the windows, and they thought when the summer would come they would be eaten to death by bitey insects.

Ireland did once have mosquitoes and malaria - but the mosquitoes died out. Cromwell died from malaria, which I'm not sure whether he picked up in Ireland or England.

I like the radical theory of human evolution, that we're evolved from a now extinct sea ape. The way we store fat is more like the way seals do than apes. Fat people in water are like seals. They float and they stay warmer longer than skinny people.
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26-02-2012, 23:15   #8
dkeely
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Solid answer
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05-03-2012, 00:42   #9
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We've been lucky, that there hasn't been a cockroach that likes our climate.


Ireland did once have mosquitoes and malaria - but the mosquitoes died out.
We have both of these in Ireland.
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