# Bell Work: What are tides? What are tides? What causes tides? What causes tides?

## Presentation on theme: "Bell Work: What are tides? What are tides? What causes tides? What causes tides?"— Presentation transcript:

Bell Work: What are tides? What are tides? What causes tides? What causes tides?

Moon and Tides? Moon and Tides? Moon and Tides? Moon and Tides?

Tides Tides are daily movements of ocean water that change the level of the ocean’s surface. Tides are influenced by the sun and the moon, and they occur in a variety of cycles.

The Lure of the Moon The gravity of the moon pulls on every particle of the Earth. The gravity of the moon pulls on every particle of the Earth. The pull is much more noticeable in liquids than in solids because liquids move more easily. The pull is much more noticeable in liquids than in solids because liquids move more easily.

The Lure of the Moon Even the liquid in an open soft drink is slightly pulled by the moon’s gravity.

Gravitational forces from both the sun and the moon continuously pull on the Earth. Gravitational forces from both the sun and the moon continuously pull on the Earth. Although the moon is much smaller than the sun, the moon’s gravity is the dominant force behind Earth’s tides. Although the moon is much smaller than the sun, the moon’s gravity is the dominant force behind Earth’s tides.

High and Low Tides How high tides get and how often they occur depend on the position of the moon as it revolves around the Earth. How high tides get and how often they occur 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.

High Tides vs. Low Tides Because of inertia, water wants to fly off of earth, but is balanced by gravity. Because of inertia, water wants to fly off of earth, but is balanced by gravity. The water that is directly facing the moon gets pulled (bulges) from the gravitational pull of the moon causing a high tide. The water that is directly facing the moon gets pulled (bulges) from the gravitational pull of the moon causing a high tide. The side directly opposite also experiences a high tide because as the moon is pulling the other side it throws off the earth’s center of gravity, causing more of a gravitational pull to be on the side with the moon. Thus the effects of inertia on the opposite side intensify or become greater because there is less of a gravitational pull. Here you also get a high tide. The side directly opposite also experiences a high tide because as the moon is pulling the other side it throws off the earth’s center of gravity, causing more of a gravitational pull to be on the side with the moon. Thus the effects of inertia on the opposite side intensify or become greater because there is less of a gravitational pull. Here you also get a high tide. When high tides occur, water is drawn away from the area between the high tides, causing low tides to form. When high tides occur, water is drawn away from the area between the high tides, causing low tides to form.

High Tides vs. Low Tides Copy this diagram into your notes in the space provided.

High Tides vs. Low Tides Bay of Fundy at high tideBay of Fundy at low tide

High Tide and Low Tide

Timing the Tides Tides occur at different spots on Earth because the Earth rotates more quickly than the moon revolves around the Earth.

Tidal Variations The sun also affects tides. The sun also affects tides. The sun is much larger than the moon, but it is also much farther away. The sun is much larger than the moon, but it is also much farther away. As a result, the sun’s influence on tides is less powerful than the moon’s influence. As a result, the sun’s influence on tides is less powerful than the moon’s influence. The combined forces of the sun and the moon on the Earth result in tidal ranges that vary based on the positions of all three bodies. The combined forces of the sun and the moon on the Earth result in tidal ranges that vary based on the positions of all three bodies.

Bell Work: What has the most influence on tides? What has the most influence on tides? What sides of the Earth has a high tide? What sides of the Earth has a high tide? Why do we not have tides on the same part of earth everyday? Explain in detail! Why do we not have tides on the same part of earth everyday? Explain in detail!

Spring Tides When the sun, Earth, and moon are in alignment with one another, spring tides occur. When the sun, Earth, and moon are in alignment with one another, spring tides occur. Spring tides are tides with maximum daily tidal range that occur during the new and full moons. Spring tides are tides with maximum daily tidal range that occur during the new and full moons.

Neap Tides When the sun, Earth, and moon form a 90º angle, neap tides occur. Neap tides are tides with minimum daily tidal range that occur during the first and third quarters of the moon. The gravitational forces on the Earth by the sun and the moon work against each other.

Neap and Spring Tides http://www.absoluteaxarquia.com/nightsky/images/tides.gif

Tides and Topography Tides can be accurately predicted once the tidal range has been measured at a certain point over a period of time. Tides can be accurately predicted once the tidal range has been measured at a certain point over a period of time. It’s a good thing that people on the beach knew when high tide occurred. It’s a good thing that people on the beach knew when high tide occurred. These photos show the Bay of Fundy, in New Brunswick, Canada. These photos show the Bay of Fundy, in New Brunswick, Canada. The Bay of Fundy has the greatest tidal range on Earth. The Bay of Fundy has the greatest tidal range on Earth.

It’s Brain Pop Time! We will watch the video on Tides. You may answer the questions as the video plays or you can wait until after the video is finished and answer the questions. We will watch the video on Tides. You may answer the questions as the video plays or you can wait until after the video is finished and answer the questions. If there is time, we will swap papers and grade them in class. If there is time, we will swap papers and grade them in class.