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The wavelength of the thermal radiation is mostly in the infrared region of the spectrum because of the environmental surface and skin temperatures.
The skin's emissivity in this wavelength range is almost unity.
63 Cal/hr is the radiative heat loss.
The skin is heated by radiation if the radiate surface is warmer than the skin surface.
If the temperature difference between the exposed skin and the environment is greater than 6 C, a person will feel uncomfortable.
The skin is heated intensely when it is illuminated by the sun or a hot object.
The simplified expression is used because the temperature of the source is higher than the temperature of the skin.
The intensity of solar energy at the top of the atmosphere is 1150 Cal/ m2.
The energy doesn't reach the surface of the Earth.
Airborne particles and water vapor reflect some of it.
A thick cloud cover can reflect up to 75% of the sun's rays.
Most of the solar radiation may reach the surface in dry deserts.
Half the body surface is exposed to solar radiation because the rays of the sun come from one direction.
As the sun approaches the horizon, the area for intercepting radiation increases, but at the same time the intensity of the radiation decreases because it passes through a thicker layer of air.
The amount of solar energy heating the skin can be large.
The emissivity of the skin depends on the color of the skin.
7 m2, subject to intense solar radiation incident at a 60* angle, receives heat at a rate of 294 Cal/hr.
If the person wears light-colored clothing, the heat is reduced by 40%.
Changing the body's orientation with respect to the sun reduces irradiation.
Camels resting in the shade face the sun, which protects their skin from the sun's harmful rays.
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