Tides

• 7% of the oceans surface is continental shelf seas
• gravity 


  natural phenomenon by which objects attract each other with a force proportional to their mass
• strength of gravity is numerically equal to the acceleration of objects under its influence
• gravity= 9.81 m/s2
• force fields is the strength of a force extended out into a plane that will weaken with distance
• Newtons First Law of Motion

  a body continues in uniform motion in a straight line unless acted upon by force
• law of gravitational attraction

  two particle of 2 masses that are a distance apart are mutually attracted by a force
• equation for force

  A) G

  B) m1m2

  C) r

  D) 2

  
• as earth orbits sun, it rotates
• moon orbits earth in 27.3 days
• lunar phases 


  different angular position of the sun
• the moon is at a 5 degree angle to the earth
• moons gravitational force acts on all parts of earth
• at any point, the strength of the moons gf is proportional to the inverse square of the distance from the earth
• oceans will always bulge directly under the moon
• equilibrium tides


  the earth experiencing two high and low tides a day
• equilibrium tides

  
• 1 bulge is from the centrifugal force, the other is from the moon
• on the other side of earth, the centrifugal force is will be stronger than the moons gravitational force
• spring-neap tides show the cycles of tides
• spring tides happen after every full and new moon and earth,moon, and sun are in line
• spring tides are large
• solar tide


  a third smaller tide when the moon and suns gravityis opposing, reducing the hight of tide
• Milanchovich cycles


  shape of earths orbit, angle of the earth, and the direction of the axis
• tides are semidiurnal
• dominant tidal period is associated with the moon
• tidal range


  difference between the high and low water tidal levels
• tidal amplitude


  half the tidal range
• tidal phase


  time of high water relative to the HW time at Greenwich
• tidal phase is measured at an angle
• long wave speed

  A) tidal amplitude

  B) V1

  C) (gD1)

  D) 1/2

  
• tidal speed slows down as the shelf depth decreases
• tidal waves get reflected by coastlines with incoming and outcoming waves interacting
• tidal resonance


  tide excites one of the resonant modes of the ocean
• tidal resonance map of UK

  
• time between tides averages at 12 hours and 25 minutes
• speed of waves depend on the depth that they were travelling
• wavelength is long compared to the depth of the ocean
• waves travel at a speed equal to √(gD) where g is gravity and D is water depth
• tidal waves are directly produced by the tide generating force