WAVES. Movement on the Seas.
The sea never seems to sit still. Its waves rise and
fall. On beaches they push forward and fall back. But what makes ocean water
into waves?
Most waves are created by the wind. The wind blows
along the surface of the water and forces waves in the same direction. The top
of a wave is called the 'crest' and the lowest part in between the crests is
known as the 'trough'. When waves roll through the open ocean, they're called
'sweel'. As they reach the shore, their crests get higher and closer together
and finally topple over. Then they're called 'breakers' or 'surf.
A gentle wind makes long waves that doesn't rise very
high. But stronger winds push harder on the water and create taller waves. Big
storms mean strong winds and that means huge, powerful waves.
Major storms at sea, called 'hurricanes' or
'typhoons', can cause enormous waves. Some are so big that they can smash
seaside houses into pieces, or tip over ships that get in their way. During
violent storms, waves have been known to reach to the tops of lighthouses and
to toss boats completely out of the water.
WAVES. Movement on the Seas.
The most destructive waves are tsunamis, but they're
quite different from other waves. Tsunamis - also wrongly called 'tidal waves'
- are not caused by tides or by the wind. These huge waves are created by
underwater earthquakes or volcanic eruptions.
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