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Tides Notes Key Question: What causes tides?
What are tides? Tides are the daily changes in the level of ocean water.
What causes tides? � Tides are caused by the difference in the gravitational force of the sun and the moon.
What is tidal force? Animation �Tidal Force: the difference in gravitational force �The tidal force exerted by the moon is stronger than the tidal force of the sun. �The moon is closer so it exerts more gravitational pull than the sun does.
High Tides �High tide is when the water level is higher than the average sea level. and Low Tides �Low tide is when the water level is lower than the average sea level.
What are tidal ranges? � A tidal range is the difference between the levels of the ocean water at high tide and low tide.
Spring Tides: �The largest tidal range �Occur during new and full moon when the sun and moon are aligned �The gravitational pull of the moon and sun add together and cause one pair of very large tidal bulges.
Spring Tides Higher high tides and lower low tides
Neap Tides �The smallest tidal range �Occur when the moon and the sun are at 90° angle to each other. �Occur during the 1 st and 3 rd quarter phases �The sun pulls water one way , the moon pulls water the other way
Neap Tides Low high tides and high low tides
What causes tidal cycles? �The Earth’s rotation and the moon’s revolution around Earth determine when tides occur. �The moon revolves slower than Earth rotates so the tides occur 50 minutes later each day. �There about 6 hours between high tide and low tide. �There about 12 hours between two high tides or two low tides.