14.4 Tides (p. 432-435)Bell Ringer: Copy Objectives

& lesson title in your IAN.1. What are the daily changes in the

level of ocean water?2. How are tides influenced by sun

and moon?3. Why/How do they occur in cycles?4. Describe the change of 2 high tides

and 2 low tides per day

The Lure of the Moon• The gravity of the moon pulls on the

water and every molecule on Earth.

• Although gravitational forces from both the sun and moon continuously pull on the Earth, the moon’s gravity is the dominate force. Why???

• Brainstorm

Size & distance

• Well, let’s compare the size: if the moon had the mass of a golf ball, the sun would have the mass of 110 school buses.

• So why is the moon’s gravitational pull still stronger?

• Gravitational pull decreases with distance. The sun is almost 150 million km away, but the moon is only 385,000km away.

High Tide and Low Tide

• The tide’s pull is strongest on the side of the Earth facing moon.

• This is called the Battle of the Bulge.

Battle of the Bulge ?

• The part of the ocean facing the moon bulges toward the moon, leaving the far side of the ocean behind.

• High tide-bulges• Low tide-area where

water is pulled awayLow Tide

High Tide

Timing the Tides

• Earth’s rotation on it’s axis and moon’s revolution around Earth determine when the tide occurs.

Click for mini video lesson!• Explanation of how

the Tides Work!• https://www.youtub

e.com/watch?v=CTQ6ciHENgI

Tidal Variations• Remember: The sun affects tides, but not

as much as moon— further away. • The combined forces of the moon & the

sun result on the tidal ranges that exist.

• Tidal range- difference between

water levels at high tide and low tide.– High tide=20 ft– Low tide=10 ft– Tidal range = 10 ft

Spring Tides:

• They are tides with the largest daily tidal range=

Highest highs, lowest lows• This occurs during the new and full moons; every 14

days• Earth, Sun and Moon in alignment

Neap Tides:

• Tides with the smallest daily tidal range between tides

• Sun, Earth, moon at 90 degree angle.

In Summary:• ***Remember your Water Wise unit test is

this Thursday! Make sure you are reviewing your Study Guide glued in your IAN. ***

• So, Let’s practice the section review as a class to review key concepts and vocabulary. p. 435

• When completed, watch the brain pop on tides to get a visual and take the quiz as a class.

• Begin review sheet for HW.