Tides review

What are tides?

Regular, predictable rising and falling of sea level caused mainly by the gravitational pull of the Moon and Sun and the rotation of Earth.

What three things affect tides?

Gravitational pull of the Moon

Gravitational pull of the Sun

Earth’s rotation and the shape of coastlines/ocean basins

How does the moon affect tides?

Its gravity pulls on Earth’s oceans, creating two tidal bulges → high tides. The Moon has the strongest influence because it is closer to Earth.

How does the sun affect tides?

Pulls on the oceans. Its effect is weaker than the Moon’s but still contributes to spring and neap tides.

When do the sun and moon’s gravitational forces work together?

During spring Tides (full moon) (new moon)

What is the position of the sun, moon , and earth during a neap tide?

What is the position of the sun,moon , and earth during a spring tide

Relate spring tides to the phases of the moon. How often do they occur?

full moon & new moon

every 2 week (twice a month)

Relate neap tides to the phases of the moon. How often do they occur?

first quarter & third quarter

every two weeks (twice a month)

Describe the diurnal tide patterns.Where can it be found in the U.S.?

1 high & 1 low tide/day (Gulf of Mexico)

Describe the semi-diurnal tide patterns.Where can it be found in the U.S.?

2 equal highs & 2 equal lows/day (U.S. East Coast)

Describe the mixed semi-diurnal tide patterns.Where can it be found in the U.S.?

2 highs & 2 lows/day of different heights (Pacific Coast)

What is a flood tide?

Water level rises → tide coming in

What is a ebb tide?

Water level drops → tide going out

What is slack water?

The brief period between flood and ebb tide when the water is still and not moving.

How are tides important to marine animals?

Bring in nutrients and oxygen

Create intertidal habitats

Help animals feed, reproduce, and migrate

Control exposure of tide pools and shore organisms