Why do I sometimes see piles of foam on the beach at the water’s edge?
While it is common to see bright white foam in the surf as waves break, there is sometimes an especially large accumulation of foam on the beach during storms. This foam line is simply the remnants of waves after they have broken. Sea foam is basically made of air bubbles separated by a film of liquid. Foam is produced when any gas, like air, is mixed into a liquid. Most of the foam that is washed up along the beaches is produced by breaking waves. As a wave breaks, the crest (or top part) of the wave forces air into the sea. The air is not stable in ocean water, and it rushes out in the form of many tiny air bubbles.
During coastal storms, as strong wind blows over the ocean, the waves get larger and contain more power. Storm waves breaking along the shoreline usually have enough energy to force enough air into the water to produce the longer lasting piles of foam. Even though the foam may look dirty and it may have an oily looking sheen, sea foam is usually harmless. There are chemical compounds in sea water, known as organic compounds, that cause the foam to be rather long lasting and durable. Additionally, even some of the salts in seawater may help to trap the air into bubbles, and eventually foam. Fine particles of sediment may attach themselves to the foam bubbles, giving it a dirty appearance.
(published 11/25/2014)
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