Ocean Waves and Tides
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Transcript Ocean Waves and Tides
Tides
Text Book Page # 366 - 371
Tides
• The daily rise and fall of Earth’s water on its
coastlines is called a tide.
• Caused by the interaction of Earth, the moon
and the sun.
• Tidal range is the difference in ocean level
between high-tide and low-tide.
Gravitational Effect of the Moon
• Two big bulges (Tidal) of water form
on the Earth:
–one directly under the moon (due to
gravity)
–another on the exact opposite side (due
to inertia)
• As the Earth spins, the bulges follow
the moon.
The Daily Tide Cycle
• One low-tide and high-tide cycle takes about
12 hours and 25 minutes.
Gravity and Tides
Low Tide
High Tide
High Tide
Low Tide
The Monthly Tide Cycle
• The changes in the position of
Earth, the moon, and the sun affect
the heights of the tides during a
month.
Spring Tides
Twice a month, at the new moon
and the full moon, the earth, the sun
and the moon lined up.
High Tides are higher and Low Tides
are lower than normal.
Tidal range is maximum.
Spring Tides
Neap Tides
At the first and third quarters the
earth, the sun and the moon pull at
right angles to each other.
High Tides are lower and Low Tides
are higher than normal.
Tidal range is least.
During new and
full moon phases
the moon, sun,
and Earth are
aligned causing a
greater
gravitational pull
on the Earth.
This results
in higher
high tides
and lower
low tides.
At the first and
third quarters the
earth, the sun and
the moon pull at
right angles to each
other.
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Tidal Energy – The Energy from Tides
Clean, renewable source of energy.
Harnessing tidal energy only possible
when tidal range is at least 4 or 5 meters.
Very few locations are suitable for tidal
power plants.
The End