The tide is high…… Where did all this water come from?

What is a tide? A tide is the: Periodic rise (flood) and fall (ebb) of large bodies of water The rise and fall of water to different levels along the shoreline

What influences earth’s tides? Tides are influenced by: Gravitational interactions between the Earth, moon, and sun Rotation of Earth Moon Cycle

Earth’s rotation Tidal interactions have slowed Earth’s rotational period. Eventually (billions of years) Earth and Moon will have the same rotational period (27.3 days) The length of the “day” is increasing. Moon’s orbit is growing Therefore, the day is getting longer, Moon looks smaller, and tides are weakening.

Moon verses sun! Tides are more influenced by the gravitational effect of the Moon than they are by that of the Sun The Moon’s closeness to us outweighs by far the Sun’s greater size Even though the sun is bigger the moon is closer 240,000 miles verses the sun 93 million miles

Effects of the sun The effect of the sun is about half that of the Moon Particularly large tides are experienced when the Earth, moon, and sun line up

Moon’s Gravity The moon’s gravitational pull influences the tides even though it is relatively weak. It pull son Earth and its surface The areas closest to the moon are pulled the strongest The Moon tries to pull on Earth to bring it closer. The Earth is able to hold onto everything but the water.

Tidal BUlge Battle of the Bulge Where the ocean is directly facing the moon, the water bulges toward the moon. The water on the opposite side gets “left behind” The bulges are called high tides.

“Bathtub effect” The Tidal Bulge occurs similar to as if you were in a bathtub full of water. If you move forward, the water moves backwards, and visa versa – if you move backwards, the water moves forward.

High and low tide How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth.

Tides can rise as much as 40 feet! Two tides occur each day About 12 hours and 25 minutes between two high tides

What are spring tides? It has nothing to do with the season or the coiled piece of steel! Comes from the German word springers, which means “to rise up” Tides that produce the greatest difference between high and low tides Occur twice a month

Spring tide Sun, moon, and Earth are all lined up in a row Causes an extreme bulge following the line of the sun and the moon High tides are at their highest Low tides are at their lowest

Spring tides

When do spring tides occur? Once at the full moon and once at the new moon When the sun, moon, and earth are nearly in a line

What are neap tides? Tides that produce the least difference between high and low tides Occur twice a month

Neap tide Sun, moon, and earth are at a right angle Sun and moon are pulling in opposite directions Water bulges slightly in the direction of the moon High and low tides are not as extreme

When to neap tides occur? Once at the first quarter and once at the third quarter When the sun, moon, and earth are at right angles to each other

Review: spring and neap tides SPRING TIDES: Highest tides. During full and new moon. NEAP TIDES: Weaker tides. During first and third quarter.

Tidal range The difference between high and low tides in distance

High tide and low tide

Tides in the Bay of FUndy

Highest tides In the world!

What is a tidal bore? The leading edge of the incoming tide forms a wave of water that travels up a river or narrow bay against the direction of the current Formed when an incoming tide rushes up a river River is flowing in the opposite direction Tidal bore develops a steep forward slope due to river’s resistance

Bay of fundy tidal bore

The Annapolis tidal generating station Uses the massive movements of the water in the Bay of Fundy Creates enough energy to power 5000 homes The only tidal power station in North America