Oceans

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Slide 1

Oceans

Water, water everywhere…

But only on the Earth!

Slide 2

Oceans

Over 70% of the Earth’s surface is covered by water

Of that, 95% is salt water – only 5% is fresh water – and part of that is ice

Slide 3

Ocean names

All the oceans are really just one body of water

This is divided into the four named oceans:

Pacific

Atlantic

Indian

Arctic

Slide 4

Tides

The oceans are always in motion

Tides happen twice daily

Tides are caused by the pull of gravity by the moon, and to a lesser degree by the sun

Why do you think the sun would pull less than the moon?

Slide 5

Currents

There are two type of Ocean Currents:

Surface Currents-Surface Circulation

These waters make up about 10% of all the water in the ocean.

These waters are the upper 400 meters of the ocean.

Slide 6

Deep Water Currents-Thermohaline Circulation

These waters make up the other 90% of the ocean

These waters move around the ocean basins by density driven forces and gravity

The density difference is caused by different temperatures and salinity

These deep waters sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase.

Currents

Slide 7

Forces

Ocean Currents are influenced by two types of forces

1. Primary Forces--start the water moving

The primary forces are:

Solar Heating

Winds

Gravity

Coriolis effect

Slide 8

2. Secondary Forces--influence where the currents flow

Surface Circulation

Solar heating cause water to expand. Near the equator the water is about 8 centimeters high than in middle latitudes. This cause a very slight slope and water wants to flow down the slope.

Winds blowing on the surface of the ocean push the water. Friction occurs between the wind and the water's surface.

Forces

Slide 9

Wind direction

Slide 10

Wind

A wind blowing for 10 hours across the ocean will cause the surface waters to flow at about 2% of the wind speed.