Tides Learning Targets: I can define tides and their importance. I can describe what influences tides. I can differentiate among the different.

Tides

Learning Targets: I can define tides and their

importance. I can describe what influences

tides. I can differentiate among the

different types of tidal patterns.

When is the best time to go beachcombing or tide pooling?

High tide or low tide?

Better check the tide tables before you head to the beach

An Introduction to Tides Tides are the rise and fall of sea level caused by the

combined effect or rotation of the Earth and the gravitation of the Moon and Sun.

Tides are long period waves that begin in open ocean and move toward shore, resulting in the rise and fall of sea level

Crest of the tidal wave = high tide

Trough of the tidal wave = low tide

http://science.kqed.org/quest/video/science-on-the-spot-watching-the-tides/

Tidal period

Continents block the westward passage of the tidal bulges as the Earth rotates

Unable to move freely around the globe, these tides establish complex patterns within each ocean basin

Why do different places on Earth see different patterns of tides?

Three basic tidal patterns occur along the Earth’s major shorelines

Most areas have two high tides and two low tides each day

Semidiurnal – two highs and lows are about the same height

Mixed Semidiurnal – highs and lows tides differ in height

Diurnal – one high and one low tide each day

Why do different places on Earth see different patterns of tides?

Harnessing Tides: Tidal Power

Hydropower that converts the energy of tides into electricity or other useful forms of power

Tidal energy is generated by the relative motion of the water which interact via gravity

Renewable

More predictable than wind or solar

The world's first commercial axial turbine tidal stream generator — SeaGen — in Strangford Lough. The strong wake shows the power in the tidal current.

Be Aware of Tides in Puget Sound

The shape of Puget Sound affects the tide as it moves through channels and inlets

In the Straight of Juan De Fuca, a 7.2 foot tide at Cape Flattery will reach Port Townsend 3 hours and forty minutes later and increase in magnitude to 7.9 feet

The tide will reach south Puget Sound 1 hour later and increase to 13.5 feet by the time the tide reaches Olympia

Extreme high tides of 18 feet have been recorded in Olympia

Tides create strong currents

In Puget Sound, the tide rushes through narrow channels and around islands creating rapids and eddies like a whitewater river

It is important for boaters and beach explorers to know what the tide is doing

Some waters are not navigable at low tide

Some beaches may also be hazardous