1. Tides

2. Tides EQ: What causes tides?
Section
Tides
EQ: What causes tides?

3. Tides
What causes tides? How can tides be used to generate electricity? Describe the positions of the sun and the moon, in relation to Earth when spring tides occur.

4. Tides
A tide is the rise and fall of the ocean’s surface caused mostly by the gravitational pull of the moon.

5. Tides
At high tide, the ocean water has risen as high as it will go on a shore.
At low tide, the ocean water has fallen as low as it can go on a shore.

6. Tides

7. Tides

8. Tides
Earth’s rotation on its axis affects which tides will occur at a certain place on Earth.

9. What causes tides?
Tides are caused by the interaction of Earth, the moon, and the sun.
The moon pulls on the water on the side closest to it more strongly than it pulls on the center of the Earth.

10. What causes tides?
The moon’s pull creates a bulge of water, called a tidal bulge, on the side of Earth facing the moon.
The water opposite the moon is pulled toward the moon less strongly than the water facing the moon.
This water is “left behind,” forming a second bulge.

11. The Daily Tide Cycle
As Earth turns completely around once each day, people on or near the shore observe the rise and fall of the tides as they reach the area of each tidal bulge.

12. The Daily Tide Cycle High tides occur about every 12 hrs. and 25 mins.
Low tides occur about every 12 hrs and 25 mins.
The time between low tide and high tide is about 6 hours.

13. Drawing of low tide/high tide for a 24 hour period.
If it is 3pm for the first low tide, six hours later it will be (the next box). Label and put time and picture. Also show the number of hours between each picture of the tides.

14. Tides occur at different locations on Earth because the Earth rotates more quickly than the moon revolves around the Earth.

15. Effects of Daily Tides

16. Photos Showing Progress of high tide coming in http://www

17. The Monthly Tide Cycle
Changes in the positions of Earth, the moon, and the sun affect the height of the tides during a month.

18. Spring Tide
Twice a month, at the new moon and the full moon, the sun and moon are in a straight line.
Their combined gravitational pull produces the greatest range between high and low tide, called a spring tide.

19. Neap Tide
In between spring tides, at the first and third quarters of the month, the sun and moon pull at right angles to each other, producing a neap tide.
A neap tide is a tide with the least difference between low and high tide.

21. The Monthly Tide Cycle

22. The Monthly Tide Cycle
Spring Tide
Neap Tide

24. The Monthly Tide Cycle
The movement of large amounts of water between high and low tide are a source of potential energy—energy that is stored and waiting to be used.
Spring tide
Full moon-highest tide
New moon
Neap Tide- half moon

25. Spring Tides and Neap Tides

26. Spring Tides and Neap Tides

27. Spring Tides and Neap Tides

28. Answers to Tides A and D C or E Spring Lower Greater
7. Neap tide – tide with the least difference between high and low tide ©
8. High tide – tide in which water reaches its highest point on the beach each day (d)
9. Spring tide – tide with the greatest difference between high and low tide (a)
10. Low tide – tide in which water reaches its lowest point on the beach each day (b)

29. Quick Check 1. What causes tides but NOT waves and currents?
A. winds and the moon’s gravity
B. mostly the moon’s gravity
C. mostly the sun’s gravity
D. only winds

30. Quick Check
2. At the full moon, the combined gravitational pulls of the sun and the moon produce a A. surface current. B. neap tide. C. spring tide. D. rip current.

31. Quick Check
3. A tide which water reaches its lowest point on the beach each day is called A. neap tide. B. high tide. C. spring tide. D. low tide.

32. Quick Check
4. Tide with the least difference between high and low tide is called A. neap tide. B. high tide. C. spring tide. D. low tide.

33. Quick Check
5. A tide in which water reaches its highest point on the beach each day is called a A. neap tide. B. high tide. C. spring tide. D. low tide.

34. Quick Check
6. If the first high tide of the day occurs at 1:00 am, the next high tide will come closest to
A. 7:00 am
B. 1:00 am the next day
C. 7:00 pm
D. 1:00 pm

35. Quick Check
7. Tide with the greatest difference between high and low tide is called a A. neap tide. B. high tide. C. spring tide. D. low tide.

36. Quick Check
8. High tides occur A. once every two days. B. once a day. C. twice a day. D. four times a day.