Figure 1. Temperature of the ocean with increasing depth

Taken from http://my.opera.com/nielsol/blog/2007/08/16/ocean-water-mixing


Question: Why Is the Ocean Blue?

Answer: When sunlight strikes water, the top 50 meters absorbs nearly all of the radiation that reaches the surface. This is why surface temperatures are warmer than at lower depths.

Light can travel up to 200 meters in depth. Surface water (within 50 meters) absorbs warm colors, like reds and oranges (long wavelength light). But, bluish light, with shorter wavelengths, continues to travel further down into the water column. Therefore, it is blue light that is scattered and reflected back. So, blue light travels further through water than red, orange, yellow, and green light. No light at all penetrates beyond 2,000 meters (3,280 feet).

If one was to take a red object under water with them, the deeper they would descend, the less red it will appear. This happens because there is a decreasing amount of red light available to reflect back to your eye. Remember that a red apple appears red because it absorbs all other colors and reflects red light. If there is no red light available, the apple will look gray or black.

See link below for an illustration of the depth at which different colors of light are absorbed.

http://oceanexplorer.noaa.gov/explorations/04deepscope/background/deeplight/media/diagram3.html

Written portion compiled by Elena Duduk from multiple, unknown sources.


Light and the Ocean Zones

The ocean is divided into three zones beginning from its surface to its furthest depth. The three zones are the following and possess the attached characteristics:

1. Sunlit Zone (Euphotic zone)

· Nearest to the surface

· About 90% of marine life exists in this zone

· Photosynthesis occurs in this zone due to enough light being able to penetrate water

· Depth ranges to 600 feet below sea level

2. Twilight Zone (Disphotic Zone)

· Little light

· No plants

· Depth ranges from 600-3,000 feet below sea level

3. Midnight Zone (Aphotic Zone)

· 90% of ocean exists in the Midnight Zone

· No light exists

· Near freezing temperatures

· Little aquatic life forms

The above information was taken from the following web link. See this resource for more information and graphics on each of the zones described.

http://www.mbgnet.net/salt/oceans/zone.htm