25. Why does the sea foam? 



Foam is made up of air bubbles separated from each other by a film 

 of liquid. Bubbles coming together in fresh water coalesce, but bubbles 

 coming together in salt water bounce off each other. 



Most bubbles in the ocean are caused by wind waves, but they may 

 also be produced by rain and even snow. The bubbles that form along 

 the seashore are very small, mostly less than 1/2 millimeter in diameter. 



When bubbles rise to the surface, they burst and release salt spray 

 into the air, a fact well known to any wearer of glasses who has been on 

 shipboard or at the seashore. Each bursting bubble causes a jet of sev- 

 eral drops to rise to heights up to 1,000 times the bubble diameter. It 

 is believed that most of the airborne salt nuclei come from bursting 

 bubbles. 



Blanchard, Duncan C. 



From Raindrops to Volcanoes, Ooubleday and Company, 1967. 



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