How does a wave form?

Answer 1

The simple answer - the wind causes waves (once in a while, of
course, there is an earthquake under the ocean that causes a "tidal wave",
or tsunami, as the Japanese call them), but all those waves that crash
endlessly on the beaches of the world, day in and day out, year after year,
are caused by winds. When you're in boat in the ocean far from land, the
waves come from every direction, because they can travel for many, many
miles, and the wind blows in different directions in different areas and
often changes from day to day. When the waves get to shallow water near the
shore, there is friction between the waves and the sea bottom. The effect
of that friction is to turn the waves so that come straighter in toward the
shore. If you're standing on a lookout point above the shore, you can often
see this effect.
Now imagine what's happening on a day when the waves are coming in
toward you even though the wind is blowing out toward the sea from the
shore. The waves breaking on shore got started someplace, possibly hundreds
of miles away, where the wind direction was more or less blowing toward the
shore, and they have continued despite having the wind now blowing at them.
At the same time, there are new waves being formed by the wind you feel,
and they will build up and head away from the shore. At some time in
next several days, they may be breaking on a beach on the other side of the
ocean, and cause some curious kid to wonder where they came from. Now you
could answer, "They started one day right off this beach."