Ocean Waves and Tides

1
Ocean Waves and Tides

• Sections 22.2 and 22.3

2
Definition of waves

• Waves- periodic up and down movements of water
  that transfer energy from one place to another

3
Factors that affect wave size

• Wave height- the vertical distance between the
  crest and the trough
• Wave period- dependent upon wavelength, the
  longer the wavelength and the slower the wave the
  longer the period, the shorter the wave, the
  quicker it moves the shorter the period

4
Wave Energy

• The longer the wind blows in the same direction,
  the more energy that is transferred from the wind
  to the water
• Larger waves have larger surface area, so are
  exposed more to wind, so carry more energy
• A swell is formed by a large group of long
  rolling waves

5
How water moves in a wave

• Water moves in a circular motion, the more
  energy, the larger the diameter of the circle
• So the deeper you go, the smaller the circles
• Wave size dependant upon duration of wind and
  speed
• Whitecaps are produced when the windspeed is so
  great it blows off the crest

6
What happens at the shore

• Breakers- when wave moves to shallow water, the
  bottom slows down, so the top ends up crashing
  over it
• Refraction- waves bend due to differences in the
  depth of water
• Undertows and rip currents- water carried back
  from the beach traveling and the bottom of the
  floor (ripcurrents are undertows that run
  perpendicular to the shore)

7
Tsunamis

• Wavelengths can get up to 240 km and can travel
  at the speed of a jetliner!
• Lots of energy- from earthquakes

8
What are tides?

• The daily change in ocean level

9
Forces the cause tides

• Gravity from the moon and the sun and the earths
  rotation

10
Tidal Behavior

• Spring tides- during full moon and new moon
  because you have gravity pulls from both the sun
  and moon
• Neap tides- when the moon is at a quarter and
  three quarters, the gravities form the moon and
  the sun offset each other causing a smaller flux
  in tide

11
Tidal Oscillations

• Are large ranges in tides because they could be
  narrow or small channels ( the change in tide
  here is very obvious)
• Along straight coastlines, you may not see much
  of a difference in tide

12
Bay of Fundy
13
Tidal Currents

• Flood tide- when tide moves toward the coast
• Ebb tide- when the tide moves towards the ocean
• Tidal bore- when ocean water fills in rivers that
  empty into the ocean