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How Waves Work
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Dear
Geographer,
Ocean waves are a complex natural phenonemon with many features
that are still
not fully understood. This how
waves work application aims to explain the basics of
wave systems, and allow you to play with the
parameters that affect their characteristics.
We hope you enjoy the experience and gain an important insight
into the fascinating world of waves.
Regards,
Andy & Devin |
Swell Generation
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Wave generation begins with the formation of a low depression.
This is a cell of air whose pressure is lower than its surroundings.
However thanks to the ever-present Coriolis force
it also features a swirling pattern of fast moving low-level
air, which generates swell by rubbing across the surface of
the water.
Coriolis force
A force due to the rotation of the Earth, which acts perpendicular
to a body's motion, causing it to turn clockwise in the Northern
hemisphere and anticlockwise in the Southern hemisphere.
Depression
Another name for an area of low pressure, caused by converging
winds, and rotating in the same direction as the earth.
Swell
Waves that have traveled out of the area in which they were
generated. Often in open sea, swell is almost invisible, despite
fairly significant transfers of energy.
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Propagation
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The transfer of energy into the surface of the water creates
swell which propagates
away from the center of the depression.
This swell travels across the open ocean, and as it does so,
the wind continues to transfer energy into the surface of the
water. The distance over which this process takes effect is
known as fetch. The distance of fetch
is an important variable in the generation of waves, as it is
largely responsible for the amount of invisible energy that
is being transfered in the swell.
Fetch
The length of an area of sea surface over which the wind blows
continuously.
Depression
Another name for an area of low pressure, caused by converging
winds, and rotating in the same direction as the earth.
Propagation
The process of waves being transmitted and travelling, becoming
distributed or widespread.
Swell
Waves that have traveled out of the area in which they were
generated. Often in open sea, swell is almost invisible, despite
fairly significant transfers of energy.
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Bathmetry
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As waves approach the coastline the wave profile
is primarily influenced by the
deep to shallow water transition
and how radical this is.
A sudden variation in depth will cause the wave to jack
up steeply as the water tries to adjust to the new
bathymetry level. Alternatively, a gentle bathymetry
gradient will cause a less high, slower breaking wave to form.
Bathymetry
The two-dimensional shape of the sea floor.
Jack up
A sudden rise in wave height, usually due to a change in the
bathymetry.
Wave profile
The two-dimensional shape of a wave.
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