Unit 8: Tides

What are tides?

The periodic rise and fall of the level of water in the ocean.

What causes tides?

The force of gravity pulls the moon and Earth (including the water on Earth's surface) toward each other. Tides are caused mainly by differences in how much the moon's gravity pulls on different parts of Earth.

What are the relationships between Moon Phases and Tides?

New & Full Moon Phases = Spring Tides

1st Quarter & 3rd Quarter Moon Phases = Neap Tides

What is the difference between Spring Tide and Neap Tide?

Spring tides occur when the sun and the moon are in line (180°) with the earth. Neap tides occur when the sun and the moon occur at right angles (90°) to the earth.

How many high tides are in a day?

Two high tides in a day

How many low tides are in a day?

Two low tides in a day

What is a tide cycle?

The changing of tides through time. At any one time there are two places with high tides and two places with low tides on Earth.

How long is each tide cycle?

A tide cycle is 24 hours and 52 minutes long (≈ one day). During this time, any point on the earth's surface experiences two high tides and two low tides.

What is a Neap tide?

The tide with the least difference between consecutive low and high tides.

What is a Spring tide?

The tide with the greatest difference between consecutive low and high tides.

What is a direct tide?

The direct tide is the high tide on the side facing the moon.

What is an opposite tide?

The opposite tide is the high tide on the side facing opposite of the moon.