Submitted by Anonymous on Thu, 05/15/2008 - 07:17
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Ocean Dynamics Beaufort Sea

2. If ice floats because it is lighter (less dense) than water, why is there ice under the water in some pictures?

From one of Mr. Harger's classes 

Wed, 05/21/2008 - 13:07

Gerty Ward

Very observant you are, Mr. Harger's class!Rick Krishfield reports: The water in the pictures are melt ponds which form in the summertime on the top surface of icefloes.  The icefloe supporting it is usually much more massive and buoyant that the melt pond, and when the melt pond gets too big it tends to run off into the ocean.
Here is more information on melt ponds.  In 8th grade science we study the concept of albedo, the reflective properties of ice and its role in the Earth's radiation balance.  As air temperatures increase, so do melt ponds (meaning ice decreases) resulting in a decrease in albedo which then increases the amount of heat absorbed by the Earth.    As this process continues, we have an excellent example of a positive feedback loop! 
Can you tell that I am a teacher?  
 A positive feedback loop is a cycle where the outcome is enhanced. Can you explain how "ice abedo feeback" is a postive feedback loop?
 Here is a hint!