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Color and Insolation
Name: Kimberly Nicole S.
Status: Other
Age: 14
Location: N/A
Country: N/A
Date: October 4, 2003
Question:
How do different colors on the earth's surface affect the amount of solar
radiation absorbed?
Replies:
Dark colors absorb energy from the sun while light colors reflect energy
from the sun. As an example, on very hot days during the summer it us
recommended that people wear light colored clothing to help them stay
cooler.
Steven Miller
Kimberly,
It is true that lighter colored surfaces (white, light green, etc.) tend to absorb less and
reflect more solar energy, while darker colored surfaces (brown, black, etc.) tend to absorb
more and reflect less solar energy.
However, the composition of the surface is also important. Conductive objects (such as metal
or concrete), can absorb more solar energy than can wood (like trees), which is a better
insulator. The characteristics of a material determine its absorptivity.
The angle at which the Sun's rays strike an object are also important, as reflection occurs
more readily when the object is
tilted to the Sun's rays (like randomly tilted tree leaves). The transmitivity of the surface
(how well the Sun's rays can penetrate) is another important factor. Water, particularly
clear water, has a high transmittivity, allowing the Sun to penetrate into the water and warm
it at greater depths than it can the soil, for instance. However, water tends to reflect
solar energy well also, reducing the amount of Sunlight that has a chance to penetrate the
water.
You can see that absorption can be quite complicated.
David R. Cook
Atmospheric Research Section
Environmental Research Division
Argonne National Laboratory
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Update: June 2012
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