英语时差：海浪的声音（下）

Whitecaps are small waves that grow too tall to support themselves on their short bases. It’s kind of like piling up dry sand on the beach. You can make a sand hill only so high before it collapses. If the base is very wide, though–as is the case with sand dunes–collapse is less likely. So waves that grow too high for their bases collapse quickly and lose their energy. This is what’s happening when you see whitish foam being tossed around out on the ocean. The longer waves, however, can support themselves better and don’t collapse. Not only that, longer waves move faster than shorter ones. So they get away quickly from the windy region where they were first formed, and roll on smoothly toward the beach.Next stop,woosh!