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