Waves and Tides

Waves and Tides

1. Waves

   • http://www.s-cool.co.uk/a-level/geography/coastal-processes/revise-it/wave-processes
   • Constructive waves
     • Also known as Swell or Surging waves
     • Depsitional
     • Long wave length
       • Up to 100m
     • Low Frequency
       • 6-8 waves per minute
     • Elliptical orbit
     • Swash is larger than Backwash
     • Low Gradient
     • Caused by distant storms
     • Create Berms
   • Destructive waves
     • Also known as surfing, storm, or plunging
     • Erosional
     • Short wave length
       • smaller than 20m
     • High Frequency
       • 10-12 waves per minutes
     • Circular orbit
     • Larger backwash than Swash
     • Steep graident
     • Caused by local winds/storms
   • Caused by:
     • The surface of the sea exerting frictional drag on the lowest layer of wind
     • The distance (fetch) travelled before the wave reaches the shoreline
     • How long the wind had blown for
     • How strong the wind is
   • Wave refraction
     • Occurs when waves approches a waveline
       • Which is a irregular coastline
     • As waves approach a coast they are refracted so that their energy is concentrated around headlands but reduced around bays.
     • Waves then tend to approach coastline parallel to it, and their energy decreases as water depth decreases.

2. Tides

   • Caused by
     • Controlled by the gravitational pull of the moon (and to a lesser extent the sun)
   • High Tide
     • The Moon pulls the water of the earth towards it, creating a bulge (High tide)
     • The Moon pulls the Earth towards it, creating a bulge of water on the otherside of the earth to the high tide
   • Spring tide
     • Twice a month, the Earth, Moon and Sun align
       • Puts an extra gravitational pull on the earth
         • Producing an extra high tide
   • Neap tide
     • Lowest tidal range
     • Occur when the Sun and Moon are at right angles to each other

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