EarthComm FluidsPages 7-11

Oceans of the WorldThere are 4 large oceans on Earth (Atlantic,

Pacific, Indian, Antarctic)All oceans have land borders (continents), but

all oceans are connected to each otherAbout 70% of the Earth’s surface is covered by

water.

Pacific

Atlantic

Indian

Antarctic

Pacific

Antarctic

Oceans of the World (Continued) The open ocean is very deep: average depth =

4-5 kmNear the bottom of the ocean it is dark, cold,

and has very high pressureDark deep ocean floor

Ocean floor in shallow waters

Ocean zones and Depths

The Warm and the Cold Ocean The ocean is layered by temperature

Upper layer = warmer water – as high as 25oC (~77oF)

Lower layer = colder water – near 0oC (near 32oF)

The Warm and the Cold OceanTemperature

of water decreases sharply between 200m and 1000m below surface

Thermocline – the zone of rapid change from warm water to cold water with increasing depth in the ocean

Similar to temperature difference noticed while treading water (top warmer, near feet colder)

Pycnocline – a layer of water in the ocean characterized by a rapid change of density with depth

Density of ocean water increases as the temperature decreases (toward

floor) Density of ocean water decreases as the

temperature increases (toward surface)

The thermocline and pycnocline happen to be approximately the same thickness in salt water due to the temperature and density characteristics

The Warm and the Cold OceanDensity

changes as depth and temperature of the water changes.

Circulation of Oceans The layer above the thermocline is

continuously circulating (moving) The deeper cold part of the ocean is

continuously circulating

Circulation of Oceans (Continued)

The circulations are different in nature

Oceanographers – scientists who study the Earth’s oceans

They have come up with many theories to account for the circulation of the oceans, and they continue to work on the complicated problem

The Wind Stress Upper layer

circulation is caused mainly by wind stress

Wind Stress – the frictional force exerted on the ocean surface by wind

The blowing wind causes waves on the water’s surface

Wind direction

The Wind Stress (Continued)

As the waves get larger the wind has more effect on them

Waves can cause problems a. Shoreline erosion b. Hazards to

ships

The Coriolis EffectWater in the ocean moves in straight lines

once set in motionEarth rotates underneath the moving water

which actually causes the water to move in a curved path

Coriolis force – the apparent force caused by the Earth’s rotation which serves to deflect a moving body on the surface of the Earth

The overall circulation of the oceans depends on the Coriolis effect