1. Tides What are they? What are they caused by? Are there different kinds of tides?

2. High TideLow Tide

3. Tides – What are they? Tides are daily changes in the level of ocean water. Tides are daily changes in the level of ocean water. They are the periodic rise and fall of the water level in the oceans and other large bodies of water. They are the periodic rise and fall of the water level in the oceans and other large bodies of water. I wonder how often this periodic rise and fall happens each day? I wonder how often this periodic rise and fall happens each day?

4. What causes tides? The gravity of the moon pulls on everything on the Earth. The gravity of the moon pulls on everything on the Earth. The moon’s gravitational pull on liquids is much more noticeable than on solids. The moon’s gravitational pull on liquids is much more noticeable than on solids. Why? Because liquids move more easily than solids. Why? Because liquids move more easily than solids.

5. What causes tides? How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth. How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth. The moon’s pull is strongest on the part of the Earth directly facing the moon. The moon’s pull is strongest on the part of the Earth directly facing the moon.

6. High Tide The part of the ocean directly facing the moon, bulges towards the moon. The part of the ocean directly facing the moon, bulges towards the moon. There is a corresponding bulge on the opposite side of the Earth. There is a corresponding bulge on the opposite side of the Earth. These bulges are called high tide. These bulges are called high tide.

7. Low Tide When high tides occur, water is drawn away from the area between the high tides, which causes low tides to occur. When high tides occur, water is drawn away from the area between the high tides, which causes low tides to occur.

8. How often is there a change in tides? Try to figure it out... High tides happen on opposite sides of the Earth. High tides happen on opposite sides of the Earth. The Earth rotates once on its axis every 24 hours. The Earth rotates once on its axis every 24 hours. How many high tides would any one place in the ocean experience each day? How many high tides would any one place in the ocean experience each day?

9. Answer The periodic rise and fall of the water level in the oceans and other large bodies of water happens... The periodic rise and fall of the water level in the oceans and other large bodies of water happens... Twice each day! Twice each day!

10. What effect does the sun have on tides? The sun is much larger than the moon. The sun is much larger than the moon. The sun is farther away from the Earth than the moon. The sun is farther away from the Earth than the moon. Q: Which one (the sun or the moon) do you think has a bigger effect on tides? A: The moon, just because it is closer.

11. Tidal Variations Tidal Range = the difference in levels of ocean water at high tide and low tide. Tidal Range = the difference in levels of ocean water at high tide and low tide. Tidal ranges vary greatly due to the combined forces of the sun and the moon on the Earth Tidal ranges vary greatly due to the combined forces of the sun and the moon on the Earth It all depends on the position of the Earth, moon, and the sun in space. It all depends on the position of the Earth, moon, and the sun in space.

12. Spring Tide A tide with a large tidal range that occurs two times a month (new moon and full moon) A tide with a large tidal range that occurs two times a month (new moon and full moon) Sun, Earth, and the moon are aligned Sun, Earth, and the moon are aligned

13. Neap Tides A tide of minimum range that occurs during the first and third quarters of the moon A tide of minimum range that occurs during the first and third quarters of the moon The sun, Earth, and moon form a 90 degree angle The sun, Earth, and moon form a 90 degree angle

14. Review Q: What are tides? Tide = the periodic rise and fall of the water level in the oceans and other large bodies of water. Tide = the periodic rise and fall of the water level in the oceans and other large bodies of water. Q: What is the dominant force that moves ocean water? The gravitational forces from both the sun and the moon. The gravitational forces from both the sun and the moon.

15. Review (cont’d) Q: Where is the moon’s pull is strongest on the Earth? The moon’s pull is strongest on the part of the Earth directly facing the moon. The moon’s pull is strongest on the part of the Earth directly facing the moon.

16. Review (cont’d) Q: What is the difference in levels of ocean water at high tide and low tide called? Tidal Range Tidal Range Q: Tidal ranges vary greatly due to the combined forces of the _________ and the ________ on the Earth Sun, moon Sun, moon

17. Review (cont’d) Q: How are the sun, Earth, and moon situated in space so that we experience a spring tide? Sun, Earth, and the moon are aligned Sun, Earth, and the moon are aligned

18. Review (cont’d) Q: How are the sun, Earth, and moon situated in space so that we experience a neap tide? The sun, Earth, and moon form a 90 degree angle The sun, Earth, and moon form a 90 degree angle