The Moon and ocean Tides

1. The Moon and ocean Tides Thanks to the pull of gravity!

2. Tidal Actions • The moon pulls the ocean waters on its closest side of the Earth causing the ocean waters to bulge toward to the moon. When this occurs we call it a “Direct High Tide”. • On the far side of the Earth from the Moon, the oceans are pulled less strongly so we call this an “Indirect High Tide”. • Halfway between these to high tides, low tides are formed as water is pulled towards the high tide areas.

3. Direct and Indirect High Tides

4. Tidal Actions • The Sun’s gravitational pull can strengthen or weaken the influence of the Moon’s gravity on Earth and tidal actions. • When the moon is in a new or full moon phase, the allignment of the Sun and Moon work together creating very high and very low tides which happen twice a month called, “Spring Tides”. • The difference between high and low tides is called a, “Tidal Range”.

5. Spring Tides

6. Tidal Actions • When the Moon is at quarter phases with the Sun at a 90° angle from the Moon, the sun weakens the Moon’s gravitational force creating a small tidal range (not very high nor very low tides). These are called, “Neap Tides”.

7. No Moon? • What would happen to Earth’s tidal Actions if there were no moon? • Check it out! Make notes to answer this questions while watching the video clip! • http://www.youtube.com/watch?v=AemGLbo8__k • “Earth Without the Moon” (6 minutes)