1. 14.4 Tides 1. daily changes in the level of ocean water 2. influenced by sun and moon 3. occur in cycles 4. 2 high tides and 2 low tides per day

2. The Lure of the Moon The gravity of the moon pulls on the water.

3. High Tide and Low Tide Pull is strongest on side of Earth facing moon

4. Battle of the Bulge The part of the ocean facing the moon bulges toward the moon. So does Earth, leaving far side of ocean behind. High tide-bulges Low tide-area where water is pulled away

5. Timing the Tides Earth’s rotation on it’s axis and moon’s revolution around Earth determine when tide occur.

6. Sun’s influence Moon = golf ball Sun = 110 school buses Why moon has more pull?

7. Tidal Variations Sun affects tides, but not as much as moon— further away. Tidal range- difference between water levels at high tide and low tide. –High tide=20 ft –Low tide=10 ft –Tidal range = 10 ft

8. Spring Tides Tides with the largest daily tidal range:Highest highs, lowest lows occur during the new and full moons; every 14 days Earth, Sun and Moon in alignment

9. Neap Tides Tides with the smallest daily tidal range between tides Sun, Earth, moon at 90 degree angle.