How waves move · Pulse Beat
A wave carries energy, not water. A cork on the sea bobs in a small circle as a wave passes and ends up close to where it started.
A wave carries energy, not water. A cork on the sea bobs in a small circle as a wave passes and ends up close to where it started.
Two numbers describe a wave: its wavelength λ (crest to crest) and its period T (the time between crests). Its speed is v = λ / T.
In deep water, long waves travel faster than short ones: v = √(gλ / 2π), where g is about 9.8 m/s². A wave 100 m long moves at roughly 12.5 m/s. That is why a distant storm sends long, fast swell ahead of the short, choppy waves.
How big waves get depends on the wind's speed, how long it blows, and the fetch, the distance of open water it blows over.
The sea on the home page is built the same way: a sum of travelling waves, each with its own wavelength and the speed the rule above gives it.