Tides Text Book Page # 366 - 371

Tides The daily rise and fall of Earth’s water on its coastlines is called a tide. Caused by the interaction (alignment) of Earth, the moon and the sun. Tidal range is the difference in ocean level between high-tide and low-tide. High Tide – When the water reaches its highest point on land. (Water level on the beaches gradually rises) Low Tide – When the water reaches its lowest point on land. (Water goes back into the ocean)

Gravitational Effect of the Moon Two big bulges (Tidal) of water form on the Earth: one directly under the moon (due to gravity) another on the exact opposite side (due to inertia) As the Earth spins, the bulges follow the moon.

The Daily Tide Cycle The Monthly Tide Cycle One low-tide and high-tide cycle takes about 12 hours and 25 minutes. The Monthly Tide Cycle The changes in the position of Earth, the moon, and the sun affect the heights of the tides during a month. Tides occur on all bodies of water, but they are most noticeable in the ocean and large lakes.

Gravity and Tides Low Tide High Tide High Tide Low Tide

The Monthly Tide Cycle – Spring & Neap tides Spring Tides Twice a month, at the new moon and the full moon, the earth, the sun and the moon lined up. High Tides are higher and Low Tides are lower than normal. Tidal range is maximum.

Spring Tides

Neap Tides At the first and third quarters the earth, the sun and the moon pull at right angles to each other. High Tides are lower and Low Tides are higher than normal. Tidal range is least.

During new and full moon phases the moon, sun, and Earth are aligned in a straight line causing a greater gravitational pull on the Earth. This results in higher high tides and lower low tides.

At the first and third quarters the earth, the sun and the moon pull at right angles to each other. This results in lower high tides and higher low tides.

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Tidal Energy – The Energy from Tides Clean, renewable source of energy. Harnessing tidal energy only possible when tidal range is at least 4 or 5 meters. Very few locations are suitable for tidal power plants.

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