1. Tides and Tsunami

2. Tides are also important physical forces in our ocean
Gravitational interactions between the sun, moon and earth are the primary causes of tides

3. What is a tide?
A tide is the periodic rise and fall of a body of water due to gravitational interactions between the sun, moon and Earth
Different positions of the sun and moon causes two different types of tides: spring tides and neap tides
Tides play an important role in the life cycle of many marine organisms

4. What causes tides?
The gravitational pull of the sun and the moon causes “bulges” on Earth that move as we rotate
Gravitational pull
“Bulge”
of Earth
Sun
Earth
Moon
Teacher’s Note: The slide labels the gravitational pull and bulge of the Earth as you advance the slide.

5. Different types of tide - Spring tides
Sun
Earth
Moon
Spring tides occur when the sun and moon are in a straight line
The tidal range is typically highest during spring tides

6. Different types of tide – Neap tides
Earth
Neap (every 15 days ) tides occur when the sun and moon form a right angle with Earth
Why is the moon’s pull greater than the sun’s?
Teacher’s Note: Even though the sun is larger than the moon, the moon’s pull is always greater because the moon is much closer to the earth.
Sun
Moon

7. Moon
Gravitational field lines from the moon

12. High tide
Low tide

16. Tsunami