Earth’s Oceans

Divisions of the Global Ocean1. Atlantic second largest

a) Average depth of 3.6 km

2. Pacific largest ocean and feature on Earth’s surfacea) Contains more than ½ of ocean water on Earthb) Deepest ocean at 3.9 km

3. Indian is the 3rd largesta) Average depth of 3.8 km

4. Southern Oceana) Coldest ocean

5. Arctic Ocean

Sea: smaller parts of ocean partially surrounded by land

Earth’s 5 Oceans

Properties of Ocean Water1. Composition

a) Salts: carried out by rivers, not returned to land when water evaporates

b) Elements: chlorine, sodium, magnesium, sulfur, calcium, & potassium

c) Dissolved gases: Nitrogen, oxygen, & carbon dioxide

2. Salinity: amount of dissolved salts in ocean water

1. Increases as temperature increases2. Removal (evaporation) of water will increase

salinity3. Adding of water (rain, rivers) will decrease

salinity

Properties of Ocean Water3. Temperature

a) Surface: temperature effected by sun, moving water underneath, & distance from the equator

a) Temperature decreases as depth increases

b) Thermocline: zone of rapid temperature change under surface water

Properties of Ocean Water4. Density: effected by temperature & Salinity5. As Depth Increases so does the Pressure6. Color: determined by the way water absorbs or reflects sunlight

WavesThe movement that carries energy through ocean.Caused by:•Wind•Tides•Earthquakes•Volcanic Eruptions

Parts of a Wave

• Crest – highest point of a wave• Trough – lowest point of a wave• Wave Height – vertical distance

between the crest and the trough• Wavelength – horizontal distance

between two crests or two troughs

Still Water

Wave Parts

Trough

Wave Height

Crest

Wavelength

Wave Movement

• When a wave passes through the ocean, individual water molecules move up and down but they do not move forward or backward.

Wave Movement

• When a wave breaks against the shore, the crest outruns the trough and the crest collapses.

• Called a breaker.• In this case, water does move

forward and backward.

Tides

•Caused by the rise and fall of sea level

•4 tides occur daily: 2 high tides & 2 low tides

•Tidal Range: Difference between high and low tide

•Intertidal Zone: area that high tide covers and low tide exposes

•Period when sea level rises: flood tide

•Period when sea level falls: ebb tide

•Period in between: slack water

Sun Tidal influence is only 46% that of the MoonDue to the much greater distance the gravitational force is reduced

Ocean Currents

•Surface Currents: Currents mainly in the top 100 to 200m of the ocean• Driven by Earth’s wind systems• Northern Hemisphere Trade winds and Westerlies blow

the Gulf Stream

•Deep currents: Caused by differences in density caused by the temperature and salinity of ocean water• Moves slowly in deep ocean • Cold, dense water sinks at the poles• After sinking these water masses slowly move away

from the poles• Eventually return to the surface through upwelling

Surface Currents

• Upwelling: upward motion of cold water occurs when surface water is moved offshore

• Downwelling: warm surface water piles up along the shore and sinks

Deep Water Currents

• Thermohaline Circulation: ocean conveyer belt • Dominant driving force is difference in density

caused by salinity and temperature• As water freezes into ice, the water that does

not freeze becomes much more saline. Water that has a high salt content is more dense and as a result will sink.

• Cold water is more dense than warm water and will sink