英語時差：海浪的聲音（上）

We’ve discussed before how waves on the ocean have the ability to reinforce other waves. First the wind starts blowing, producing small waves. Some of these small waves combine with other small waves to form a single, larger wave. This is how you get a choppy sea. But anyone who loves the beach can tell you about the distinctive sound of the ocean hitting the sand: Woooosh. That woosh is telling us something: it’s telling us that long waves are the ones hitting the beach, not small and choppy ones! How is it telling us that? There’s an interesting culling process that takes place out in the ocean where waves are being formed. Small waves combine together to form larger waves, but depending on how long the waves are, there’s also the possibility of forming a whitecap.