Tides

I.  Tides are the daily fluctuations in sea level that are caused by
    A.  The gravitational pull of the sun and the moon
    B.  The spin of Earth
   
II.  Tidal bulges are rises in sea level
    A.  A bulge occurs on the side closest to the sun or moon because of its close proximity to the gravitational source.
    B.  A bulge occurs on the side of Earth immediately opposite the side closest to the sun or moon because it is further away, where the gravitational source is weakest.  The spin of Earth also helps this opposite bulge to occur.

III.  Types of tidal cycles.
    A.  Diurnal --
          1.  One high tide, one low tide in 24 hour period.
          2.  Could likely occur at high latitudes
    B.  Semidiurnal --
            1.  Two high tides, two low tides in 24 hour period, each tidal level reaching about the same level.
            2.  Could likely occur at lower latitudes.
    C.  Mixed --
            1.  Two high tides, two low tides in 24 hour period, each tidal level reaching a different height or level.
            2.  Could likely occur at mid latitudes.

IV.  Types of tidal extremes
    A.  Spring tides -- day of highest high tides and lowest low tides (greatest tidal extremes)
        1.  Occurs when Earth, Moon, and Sun are aligned
        2.  Occurs at either New Moon or Full Moon phase.
    B.  Neap tides -- day of lowest high tides and highest low tides (least tidal extremes)
        1.  Occurs when Earth, Moon, and Sun form a 90o degree angle
        2.  Occurs at either First or Third Lunar phases.