By Rumi Johnson

and Carrie Chen

TerrificTides

Tides are the periodic changes in the water level of Earth’s oceans, gulfs, and bays. The gravity of the Sun and moon both contribute to increasing and decreasing the level of these bodies of water. Since the Sun is 360 times further away from the Earth than the moon, the

moon has a much larger effect when producing tides than the Sun. Most parts of the world experience two

high tides and two low tides every day, which is called a semi-diurnal tide. Some places experience one high

tide and one low tide every day, which is called a diurnal tide. When a tide occurs in a location, the flip side of that place on Earth also experiences the same

thing.

What are tides?

DID YOU KNOW?

• The shape of a coastline and the shape of an ocean floor determines if it has two high/low tides per day or only one.

• High and low tide times differ by about 50 minutes from the previous day since the earth rotates faster than the moon.

• The lowest tidal range (difference between high and low tide) occurs in the deepest part of the ocean.

• The highest tidal range in the world is in the Bay of Fundy in Nova Scotia, Canada at about 15 meters.

• The gravitational pull of the Moon and Sun DO have an effect on land, but it’s less noticeable than with water because land is less flexible than water.

?

?

?

?

?

?

When were tides discovered?

Tides were discovered over 300 years ago by Isaac

Newton. He developed a theory called “The Equilibrium

Theory of Tides” which suggests that every object exerts a pull on every other

object.

Types of Tides

Neap TidesSpring Tides

When the gravitational forces of the moon and Sun combine, a Spring tide is formed. When the Earth, moon, and Sun form a right angle, a Neap tide

is formed.

Neap tides occur when the Earth, Moon, and Sun form a right angle. They happen during a first or third

quarter moon twice a month. During a neap tide, the difference between the height of the water at

high and low tide is least.

Neap Tides

Spring tides occur when the Earth, Moon, and Sun are lined up. The gravitational pull of both the Sun and Moon are pulling in the same direction, so during a Spring tide,

high and low tides are more EXTREME than normal. Spring tides occur during full and new

moons.

Spring Tides

We Hope You Enjoyed Our Presentation!