1. Bell work If the moon had the mass of a golf ball, the approximate mass of the sun would be about 110 school busses! Even though the moon is smaller than the sun, the moon most influences the Earth’s tides. Can you guess why this might be?

2. Tides

3. Objectives for today 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions.

4. What causes tides? Gravity! Gravity! The gravity of the moon pulls on the waters of Earth. The gravity of the moon pulls on the waters of Earth. The gravity of the sun pulls on the waters of Earth. The gravity of the sun pulls on the waters of Earth. Then why does the moon have a greater effect on the tides? Then why does the moon have a greater effect on the tides? –The moon is closer!

5. The gravity of the moon pulls on every particle of the Earth. The pull on liquids is much more noticeable than on solids, because liquids move more easily. Tides are the daily changes in the level of ocean water. These tides are influenced by the sun and moon. High Tide and Low Tide How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth.

6. Battle of the Bulge When part of the ocean is directly facing the moon, the water there bulges toward the moon. At the same time, water on the opposite of the Earth bulges because of the rotation of the Earth and the motion of the moon around the Earth.

7. High tide occurs on the part of the Earth that is closest to the moon. Concurrently, high tide also occurs on the opposite side of the Earth.

8. Objectives for today 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions.

9. How often do tides occur? There is a high tide about every 12 hours and 25 minutes. There is a high tide about every 12 hours and 25 minutes. –So there are 2 high tides every day. There is a low tide about every 12 hours and 25 minutes. There is a low tide about every 12 hours and 25 minutes. –So there are 2 low tides every day. There is a high tide, then about 6 hours later a low tide, then a high tide, then a low tide. There is a high tide, then about 6 hours later a low tide, then a high tide, then a low tide.

10. Timing Tides The rotation of the Earth and the moon’s orbit determine when tides occur. Tides occur at different locations because the Earth rotates more quickly than the moon revolves around the Earth.

11. The sun also affects tides. Because the sun is much farther away, its influence is less powerful than the moon’s. The combined forces of the sun and the moon result in tidal ranges that vary based on the position of all three bodies. A tidal range is the difference between levels of ocean water at high tide and low tide. Tidal Variations

12. Low tide Low tide High Tide

13. Spring tides occur at the new and full moon when the sun, Earth, and moon are aligned. Springs tides have the largest daily tidal range. Neap tides occur when the sun, Earth, and moon form a 90° angle. Neap tides have the smallest daily tidal range. Tidal Variations, continued

14. Objectives for today 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions.

16. When the moon is new or full, the gravitational forces of the sun and moon are pulling at the same side of the earth. (See the diagram below.) This occurrence creates the extra large "spring" tides. When the moon is at first and third quarter, the gravitational forces of the sun and moon are pulling at 90 degrees from each other. (see the diagram below.) This occurrence yeilds little net tides called neap tides.

17. After a tidal range has been measured, the times that tides occur can be accurately predicted. This data can be useful for people who live near the coast. In some coastal areas with narrow inlets, movements of water called tidal bores occur. A tidal bore is a body of water that rushes up through a narrow bay, estuary, or river channel during the rise of high tide and causes a sudden tidal rise. Tides and Topography

18. Objectives for today 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Produce a model to demonstrate how the moon produces tides. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. 0607.6.5 Illustrate the positions of the earth, moon, and sun during specific tidal conditions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions. SPI 0607.6.5 Predict the types of tides that occur when the earth and moon occupy various positions.