The Color We See
Our eyes are able to see the color that is
reflected or scattered off an object. We cannot
usually see the colors that are absorbed by an
object. If all light reflects off an object, the
object appears white. If all light is absorbed by
an object, the object appears black. A red crab
appears red because it reflects red light and
absorbs all other colors.
The Blue Ocean
The Blue Sky
When sunlight enters the atmosphere, it is
absorbed or scattered by molecules and particles.
The short wavelengths of visible light; blue, green,
and violet, are scattered by air molecules more
frequently than the long wavelengths; red, yellow,
and orange. The sky looks blue, rather than green
or violet, because human eyes are most sensitive
to blue light.
When sunlight enters the ocean, it is absorbed
or scattered by molecules and particles. The
ocean looks blue because the molecules and
particles in water absorb red light first and then
blue light. The ocean’s color is also dependent
upon the color of the sky. On a day when the
sky is bright blue the ocean appears blue, but on
a cloudy day the ocean appears gray.
Did You Know?
Underwater all things
appear blue because
blue light penetrates
deepest in the ocean.
Hazy Air vs. Clear Air
Clear air becomes hazy when tiny particles are
present in the air. The distance visible light is able
to travel is dependent upon the clarity of the air. If
the air is hazy there are more molecules, so there
will be more scattering and the visible light will not
travel very far. If the air is clear there are less
molecules and there will be less opportunities for the
visible light to scatter, allowing it to travel farther.
1. Ahrens, C. D. (2005). Essentials of Meteorology: An Invitation to the Atmosphere (4th ed.). California: Thomson.
2. Chase, V. (2007, January 24). Learning Ocean Science through Ocean Exploration: Section 5 - Ocean Zones. NOAA. Retrieved July 2, 2007, from http://oceanexplorer.noaa.gov/edu/curriculum/section5.pdf
3. Ocean Explorer. (2006, March 21). NOAA. Retrieved July 5, 2007, from http://oceanexplorer.noaa.gov/explorations/04deepscope/background/deeplight/media/diagram3.html
4. Stewart, R. H. (2005). An Introduction to Physical Oceanography. Texas: Texas A & M University.
Cloudy Water vs. Clear Water
Water located in the middle of the ocean is a
very clear, deep, dark blue whereas, water
located along the coast is much more cloudy
and murky in appearance. In the clearest water,
10% of the visible light that passes through the
surface of the ocean can travel down 90 meters.
In coastal water, however, visible light does not
typically travel deeper than a few meters.
Created by Leeanne Hazzard & Fabrice Veron, 2007
Air-Sea Interaction Laboratory
College of Marine and Earth Studies
University of Delaware