1. Tides
Section 13.2

2. What are tides?
The daily rise and fall of Earth’s waters on its coastline
High Tide – when water reaches its highest point on shore
Low Tide – When water reaches its lowest point on shore

3. What are tides?
Tides occur in all bodies of water but are most noticeable in large lakes and oceans
Tides occur on Lake Superior, too

4. What causes tides?
Tides are caused by gravity between the Earth, moon, and sun

5. What causes tides?
The moon’s gravity pulls on Earth’s surface closest to the moon causing water to create a bulge
Water is stolen from the sides to create the bulge
The side of Earth furthest from the moon has the least effect of moon’s gravity and is acted on by centrifugal force
video

6. Different kinds of tides
Most coastlines experience 2 high tides that are about 12 hours 25 minutes apart

7. Different kinds of tides
The sun’s gravity can add to the moon’s pull or even it out depending on the positions of the sun, moon and Earth

8. Different kinds of tides
Spring Tides
- highest high tides, lowest low tides
- sun, moon, & Earth are in line
Neap Tides
- lowest high tides, highest low tides
- sun, moon, & Earth are at right angles

9. Spring Tide
Neap Tide

10. High and low tides are affected by:
Landforms that interrupt water movement
Basins at the mouth of a river
The depth of moving water in a narrow channel

11. Using Tides
Potential energy from tide heights can be harnessed to create electricity
Tidal Plants
Hydroelectric
Dam

12. Bay of Fundy
The tidal difference is 25 feet