Ocean Currents

Phenomenon

In general, ocean currents on the west side of a continent are cool currents and ocean currents on the east side of a continent are warm currents. Why?

The temperature of an ocean current can affect coastal climates, View the video to observe a model of major ocean currents.

Note how salinity and temperature affect ocean current flow.
Describe patterns you observe regarding the location of warm and cold currents, for example, location relative to east or west coasts of continents, or latitudes.
Use EARTH to observe ocean currents. Describe patterns you observe.
Analyze two climographs to observe how ocean currents may be affecting climate.
Next use a model to observe the causes of ocean currents.

Ocean Current Model

Climate: Warm versus Cold Ocean Current

Ocean water warms in the tropical regions. and moves in currents from the equator. The path of the current curves because of the Coriolis effect caused by Earth's rotation.

Water cools at the poles becoming denser. Cool currents flow from the polar regions to the equator.

Note the pattern of cold and warm currents. Warm currents tend to located on the eastern side of continents. Gold currents tend to located on the western side of continents.

Image Credit: NOAA

Compare the climographs of Los Angeles and Charleston.

Explain how ocean current temperature affects the climate at each location.

Annual Climatology: Los Angeles, CA (LAX)

Elev: 100 ft Lat: 33^o 56'N Long: 118^o 24'W

Cold Current

Annual Climatology: Charleston, SC (CHS)

Elev: 40 ft Lat: 32^o 54'N Long: 80^o 02'W

Warm Current

Ocean Conveyor System

Phenomenon #1- The Ocean Conveyor Belt

Use the model to observe the relationship between temperature and salinity.

Salinity and Temperature Connection

Are you surprised to see that there is only one ocean even though as humans have divided it into multiple geographic regions? (image source: The M Factory © Smithsonian Institution)

Annimation of thermohaline circulation without narration.

Most of the Earth's surface is covered by salty ocean water. Scientists at Woods Hole Oceanographic Institute have studied the three dimensional circulation of ocean water. Differences in temperature (thermo) and salinity (haline) lead to a thermohaline circulation pattern in which warm water moves across the surface and cold water sinks below the surface.

As ocean water warms, it expands. Because density is mass divided by volume, the increased volume decreases the density of the ocean water. The increase in volume also decreases the concentration of salt in the water. The change in density allows warm ocean water to float to the surface.

At the surface, warm ocean water evaporates becoming cooler from heat loss into the atmosphere. As water evaporates, it leaves behind salt increasing the concentration of salt in the cooler ocean water. Water volume condenses as it cools A decrease in volume leads to a increase in density.

The density of the ocean water increases both from cooling and from higher salt concentration. The cooler, denser water sinks below the warmer surface water.

Sea ice also plays an important role in the thermohaline circulation. of ocean water. When surface water freezes, the salt remains in the unfrozen liquid water. Climate scientists are investigating and modeling the potential climate impacts as Arctic sea ice coverage changes.

Learn more by reading "Study Finds Surprising New Pathway for North Atlantic Circulation."

Phenomenon #2 Seawater Expansion

Use a model to observe seawater expansion.

Use the red food coloring to make observations easier.
Add room temperature salt water to the top of the Snapple iced tea bottle. Then cap the bottle.
Warm the water using a heat source (hot water bath or lamp).
Observe what happens.

Materials

Sturdy plastic Snapple iced tea bottle.
salt water
Snapple bottle cap with hole drilled and pipette inserted.
heat source

Ocean Recipe: 6 teaspoons of salt to 1 liter of water.

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