Wind is the great maker of waves. There are exceptions  , such as the tidal   waves sometimes caused by earthquakes under the sea. But the waves most of us know are caused by winds blowing over the sea . Now let's learn some physical   things about it. A wave has height, from low point to high point . It has length  --the distance from this high point to that of the following wave. The period of the wave means the time it takes for succeeding high points to pass a fixed point. None of these things stays the same--for all depend upon  the wind, upon the depth   of the water and many other matters. The water that makes up a wave does not advance with it across the sea. Each drop of water turns around in a little circle with the passing of the wave, but returns very nearly to its original position  . And it is lucky that this is so. For if the huge groups of water that make up a wave really moved across the sea, sailing would be impossible. If we want to find the speed of a wave, we may use the following way : Speed =" wavelength" x frequency  . Here, wavelength is the distance between two high points , frequency means the number of cycles per second Where can we find this passage?
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