# You only need to make sure you have written down what is in bold and underlined.

## Presentation on theme: "You only need to make sure you have written down what is in bold and underlined."— Presentation transcript:

You only need to make sure you have written down what is in bold and underlined

Tides  Tides are the rise and fall of water – rise for about 6 hours then fall for about 6 hours http://serc.carleton.edu

What Causes Tides  The Earth and the moon are pulled towards each other due to the force of GRAVITY  Tides occur because the moon does not pull with the same force on all parts of the Earth  2 high tides at any one time – one at point on Earth closest to moon and one on the opposite side of Earth http://www.das.uchile.cl/~mhamuy/moon.html

High Tides  Point A: Moon’s gravitational force on the water is greater than its force on the Earth as a whole  Water here is pulled more strongly towards the moon than the Earth = high tide A B C D

High Tides  Point B: The moon’s gravitational force on the Earth as a whole is stronger than its force on the water  The Earth is pulled more strongly towards the moon and the water is “left behind” = high tide A B C D

The Tide Cycle: Low Tides  Points C and D: Water flows away from these locations towards points A and B = low tide A B C D

2 High and 2 Low Tides Every 25 hrs due to Earth’s rotation http://www.pbs.org/wgbh/nova/venice/tide_ curiosities.html

Spring and Neap Tides  The Sun’s gravity also pulls on Earth’s waters  Sometimes the sun’s and moon’s gravity work together = spring tide (A)  Sometimes they pull on the water at right angles = neap tide (B)  Spring and Neap tides both happen twice a month http://www.das.uchile.cl/

Spring Tide  during full & new moons  highest high tides & lowest low tides  Biggest tidal range (difference between high and low tide) http://www.huntsmanmarine.ca

Neap Tide  Neap tide: during first & last quarter moons  High tides not very high and low tides not very low  Smallest tidal range http://www.huntsmanmarine.ca

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