14.4 tides (p. 432-435) bell ringer: copy objectives & lesson title in your ian. 1. what are the...
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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.