1. Tides
Tides are daily changes in the elevation of the ocean surface (sea level)
Ocean tides result from the gravitational attraction exerted upon Earth by the moon and, to a lesser extent, by the Sun
The force that produces tides is gravity

2. Tidal Bulges on the opposite sides of the earth are Caused by the Moon
Not to scale

3. MORE change between high and low tides
Tide Cycle
Spring tides have the greatest tidal range due to the alignment of the Earth–moon–sun system.
MORE change between high and low tides
(greater tidal range)

4. LESS change between high and low tides
Tide Cycle
Neap tides have the lowest tidal range and occur during ¼ and ¾ phases of the moon
LESS change between high and low tides
(smaller tidal range)

6. Tidal Patterns #1 diurnal tide
A tide in which there is only one high water and one low water each lunar day

7. Tidal Patterns #2 semidiurnal tide
A tide having two high waters and two low waters during each lunar day (most common)
(Tides are of approximately Equal Heights!)

8. Tidal Patterns #3 mixed tide
A mixed tide has uneven heights of the two high tides and/or the two low tides each lunar day

9. Global Tides