Tides

Open Ended

What are tides?

What Are Tides?

⚫Tides are the daily rise and fall of Earth’s

waters on its coastlines.

⚫As the tide comes in, the level of water on

the beach rises, and as the tide goes out, the
level of water on the beach goes down.

What

Causes Tides?

The gravitational pull from the Moon, and the
rotation of the Earth on its axis, cause the ocean

and sea water to bulge, producing the tides.

Since the Moon is close to the Earth, it has

a strong gravitational pull on it (closer

objects have a stronger gravitational pull).

Multiple Select

What causes the tides? (More than one answer)

• Gravity

• Earth's Rotation

• Black holes

• Evaporation

Multiple Choice

Why does the moon's gravity affect the tides more than the Sun's gravity?

• Because the moon is bigger than the Sun

• Because the moon is smaller than the Sun

• Because the moon is closer to Earth

• Because the moon is farther from Earth

⚫ The Moon pulls on the water on the side nearest to it

more strongly than it pulls on the centerof the Earth.

⚫ This pull creates a bulge of water on the side of Earth

facingthe the Moon.

“Bulge” of Earth

Sun

Earth
Moon

Gravitational pull

17

⚫ The water on the side of Earth facing away from the

Moon has a less strong pull.

⚫ As Earth rotates, different places on the planet’s

surface pass through the areas of the tidal bulges
and have the change in water levels.

The Earth rotates one full turn in 24 hours,
but the bulge of water stays on the side of
the Earth facing the moon. The bulge stays

in place as the Earth moves under it.

High tide

In places where there are tidal

bulges, high tide is occurring along

the coastlines.

High
Tide

High
Tide

In places between the tidal bulges, low
tide is occurring along the coastlines.

Low Tide

Low Tide

Sun’s Gravity and Tides

⚫ The Sun is so large that its

gravity also affects tides.

⚫ At times, the Sun and Moon

pull together on Earth’s
waters in the same direction.

⚫ At other times they pull in

different directions.

Changes in the positions of Earth, the

Moon, and Sun affect the height of tides

during a month.

Multiple Select

When do spring tides occur?

• Twice a month

• During a full moon

• During a quarter moon

• During a new moon

Multiple Select

When do neap tides occur?

• Twice a month

• During a full moon

• During a quarter moon

• During a new moon

⚫Spring tides occur 2 times a month, during a

full and new moon when the Earth, Sun, and
Moon are lined up.

⚫Spring tides are higher and lower than normal

tides.

Spring Tide

Spring Tide

Low Tide

Low Tide

High Tide

High Tide

New Moon

Full Moon

Draw

Draw where the sun, moon and Earth have to be to create a Spring Tide

⚫ Neap tides occur in between spring tides, at the

first and third quarters of the Moon when the
Sun and Moon pull at right angles to each other.

⚫ Neap tides are not

as high or low as
normal tides.

Neap Tides

Neap Tide

Low Tide

Low Tide

High Tide

High Tide

First Quarter

Moon

Third Quarter

Moon

Draw

Draw where the sun, moon, and Earth have to be to create a neap Tide

“Strong Tides”

“Weak Tides”