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Outdoor Temperature Measure
Name: Nic
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: N/A
Question:
In regard to outside temperature, I have read a couple
articles describing how temperature is typically taken outside in a
ventilated box hovering over the grass ground for true temperature.
Is there some base temperature difference between that measurement
and direct sunlight? I can imagine there is a variation, but if it
is 100 degrees outside, no clouds, mid day and no wind at all, what
would the difference likely be? Is there a ratio or general
variation?
Replies:
Nic,
The temperature of a thermometer or temperature sensor
can properly reflect the air temperature only when the
sensor is in the shade and is ventilated. The reason is that
sunlight shining on a temperature sensor will warm it up to
well above the actual air temperature.
So, there is usually a large difference between the ventilated
temperature measurement and the temperature of an object exposed
to sunlight. Depending on the characteristics of the object that
is heated by the Sun, the temperature difference between a ventilated
temperature sensor at 100 degrees Fahrenheit and an object in the Sun
can easily be 40 degrees Fahrenheit or more. This is easily seen if
you place a piece of metal in bright sun for a short In fact it may
be too hot to touch without burning your skin. This is critically
important for people who are exposed to sunlight, as the Sun can warm
your skin to well above your normal skin temperature, causing
drying of the skin and eventually a sunburn, as well as the possibility
of dehydration and sunstroke.
David R. Cook
Meteorologist
Climate Research Section
Environmental Science Division
Argonne National Laboratory
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Update: June 2012
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