Tides and the moon What causes tides? Neap tides vs Spring tides: Create a venn diagram or comparison chart for Neap tides and Spring tides

Tides… the gravitational attraction among Earth, the Moon and the Sun. Tides are caused by… the gravitational attraction among Earth, the Moon and the Sun. 1. Tides are… the periodic rise and fall of sea level. a. High tide… highest level to which the water rises b. Low tide… lowest level of the water 2 2

2. What forces & heavenly bodies cause the tides? GRAVITY! gravitational pull of Moon on oceans facing it causes high tide Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon (and away from the water on the far side). The Cause of Tides… 3 3

Why are there tides on both sides? As gravitational force acts to draw the water closer to the moon, inertia attempts to keep the water in place. But the gravitational force exceeds it and the water is pulled toward the moon, causing a “bulge” of water on the near side toward the moon (Ross, D.A., 1995). On the opposite side of the Earth, or the “far side,” the gravitational attraction of the moon is less because it is farther away. Here, inertia exceeds the gravitational force, and the water tries to keep going in a straight line, moving away from the Earth, also forming a bulge (Ross, D.A., 1995).

What else? the sun’s tide-generating force is about half that of the moon Because the earth rotates on its axis the moon completes one orbit in our sky every 25 hours (Not to be confused with moon's 27 day orbit around the earth), we get two tidal peaks as well as two tidal troughs. These events are separated by about 12 hours. Since the moon moves around the Earth, it is not always in the same place at the same time each day. So, each day, the times for high and low tides change by 50 minutes.

The Cause of Tides… 3. What motion causes tides at location to change every 6 hours? Earth’s rotation on it’s axis every 24 hours and… Moons rotation every 24 hours and 50 minutes and… 4. The times of tides vary each day because the moon orbits the Earth every 28 days 6 6

Earth rotates through two tidal bulges every lunar day There are two high tides and two low tides every 24 hours 50 High tides occur 12 hours and 25 minutes apart. It takes six hours and 12.5 minutes for the water at the shore to go from high to low, or from low to high.

http://loneswimmer.com/2010/08/23/tides-for-swimmers-part-1-theory/#jp-carousel-535 Spring Tide… Twice a month, the Earth, Moon, & Sun align (line up) causes the Moon & Sun to pull together on Earth’s oceans. Higher high tides / lower low tides 8

Neap Tide… Twice a month, the Earth, Moon, & Sun will form a right angle which causes the Moon & Sun to pull from different directions on Earth’s oceans. Evens the tides http://www.yourdictionary.com/neap-tide 9

Compare the Spring Tides & Neap Tides http://csep10.phys.utk.edu/astr161/lect/time/tides.html Compare the Spring Tides & Neap Tides 10