Joke of the Day

Q: How does a man on the moon get his haircut?

A: Eclipse it!

Agenda

Go over homework from last night Review last lesson a little bit Lesson on Tides Video clips Independent Practice Exit Ticket

TIDES

Objectives For Today

By the end of today…

SWBAT explain the difference between tides and waves and explain how the moon affects Earth’s oceans.

SWBAT explain how the orientation of the Moon and Earth create high tides and low tides on Earth.

What is a tide?

What is the difference between a tide and a wave?

Key Point #1: A tide is the regular rise and fall of the level of the ocean water, while a wave is a raised line of water that moves across the surface of the ocean.

Key Point #1: A tide is the regular rise and fall of the level of the ocean water, while a wave is a raised line of water that moves across the surface of the ocean.

Tides Bay of Fundy – Nova Scotia17 meters (record)

What causes tides and waves?

Key Point #2: A tide is caused by the effects from the Moon, while a wave is generally caused by the wind.

So another difference between tides and waves is the different ways they are formed.

Waves in the ocean are sometimes called “wind waves,” or, more precisely, “wind-generated waves”

Key Point #2: A tide is caused by the effects from the Moon, while a wave is generally caused by the wind.

So another difference between tides and waves is the different ways they are formed.

Waves in the ocean are sometimes called “wind waves,” or, more precisely, “wind-generated waves”

Tides: What does the Moon have to do with it?

Key Point #3: Tides occur mainly because of differences in how much the moon pulls on different parts of the Earth.

The force of gravity pulls the moon and Earth, including the water on Earth’s surface, towards each other.

The moon’s gravity pulls water from the Earth’s oceans and also the Earth itself towards the moon.

Key Point #3: Tides occur mainly because of differences in how much the moon pulls on different parts of the Earth.

The force of gravity pulls the moon and Earth, including the water on Earth’s surface, towards each other.

The moon’s gravity pulls water from the Earth’s oceans and also the Earth itself towards the moon.

HIGH TIDES AND LOW TIDES

High tide vs. Low tide

Key Point #4: At any one time, there are two places with high tides and two places with low tides on Earth.

A high tide occurs when ocean levels are elevated.

A low tide occurs when ocean levels are lowered.

Sea level is average height of an ocean’s surface

Key Point #4: At any one time, there are two places with high tides and two places with low tides on Earth.

A high tide occurs when ocean levels are elevated.

A low tide occurs when ocean levels are lowered.

Sea level is average height of an ocean’s surface

There are two high tides…How do they occur? Key Point #5: There are two high tides on

Earth, one on the surface closest to the moon and one on the opposite side.

How do they occur? : The moon’s gravity pulls water toward the point on Earth’s surface closest to the moon.

Key Point #5: There are two high tides on Earth, one on the surface closest to the moon and one on the opposite side.

How do they occur? : The moon’s gravity pulls water toward the point on Earth’s surface closest to the moon.

Two high tides…two reasons

But, if the moon’s gravity were the only cause, there would only be ONE high tide at a time.

But, if the moon’s gravity were the only cause, there would only be ONE high tide at a time.

A

B

The force of the gravity at this point is stronger than the force of the moon’s gravity on Earth as a whole.

Water near point A is pulled more toward the moon more strongly than is Earth as a whole.

A high tide forms.

The force of the moon’s gravity at this point is weaker than on Earth as a whole.

Earth as a whole is pulled toward the moon more strongly than the water at point B, so the water is “left behind”

A high tide forms.

Low tides

Low tides are located on the two surfaces of the Earth that are 90 degrees to the moon.

How are they formed? : Water flows away

from the two other sides of the Earth, causing low tides to occur.

Low tides are located on the two surfaces of the Earth that are 90 degrees to the moon.

How are they formed? : Water flows away

from the two other sides of the Earth, causing low tides to occur.

High tide(Direct tidal BULGE)

High tide(Indirect tidalBULGE)

Low tide

Low tide

Moon

Exit Ticket

Draw this diagram and label the locations of where the high tides and low tides would be on Earth.

Moon

Earth