The normal human body temperature
is usually between 36°C and 37°C
and is quite sensitive to changes in external temperature
But why does
37°C water feel cool
while at 37°C air temperature
people feel unbearably hot?
Brief Summary
Qian Guanyu
Department of Dermatology,
Third People’s Hospital, Jiangsu University
The human body primarily dissipates heat through the skin via radiation,
sweating, and evaporation
to maintain stable body temperature
However, the skin’s perception of hot and cold
does not solely depend on temperature values
The rate of heat loss or gain is more critical
Water is an excellent heat conduction medium
with a thermal conductivity efficiency 24 times that of air
When bathing, even if the water temperature
is the same as the core body temperature
the water flowing over the skin
will still rapidly carry away heat
Once the skin senses
that heat is being lost too quickly
it will feel “cool”
Especially when the water flow is strong
the cooling sensation becomes more pronounced
In high-temperature weather, even if the air temperature
is similar to the core body temperature
there is no temperature difference between the body and the environment
and the efficient heat conduction medium
the skin’s radiative cooling function
becomes less effective
If the air humidity is slightly higher
the sweat that cools the body
will struggle to evaporate
and the remaining cooling function of the skin
will also “cease to function”
At this point,
the heat continuously generated by our body
cannot be dissipated
leading to inevitable discomfort
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Related Reading
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Editor: Wu Tong
Reviewed by: Lin Lijun
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