•  To identify some of the earth's ocean currents that influence weather
•  To investigate the effects of ocean currents on the earth's weather
   

What factors most influence the earth's daily weather patterns?

Wind, currents, seasons, warm and cold fronts, topography and ocean currents all affect the earth's weather.   Water currents  play a role in maintaining the steady balance of temperatures we experience on earth. These currents are chiefly driven by the wind.  Without ocean currents, the tropics would gradually grow hotter and the Arctic would progressively become colder. The global pattern of currents is one of amazing symmetry. 

In the Northern Hemisphere,  there exist gyres, which are rotating whorls of surface currents.   In each of the gyres, which are thousands of miles across, warm water moves up the western side of the ocean and cools in the higher latitudes.  It then flows down the eastern side of the ocean toward the equator, where it is warmed.

Warm Ocean Currents 

The Gulf Stream is water from the tropics that flows along the east coast of the U.S. into the North Atlantic.  The North Atlantic Drift is a northern extension of the Gulf Stream that warms Iceland & Norway.  The Irminger Current is the northernmost extension of the Gulf Stream that brings warm water to the Arctic. 

The Kuroshio is the Pacific’s equivalent to the Gulf Stream.   The warm waters of the Kuroshio are brought toward the Americas by the North pacific current.   

Waters from the East Coast of Africa that flow northward in June and August and reverse direction during the winter are called the Somali Current.   

Off the Brazilian coast, the South Equatorial Current flows westward. 

At the equator, the Equatorial Counter-Current is formed when the Trade Winds build up warm waters on the western side of the oceans, and they flow eastward restoring balance.   El Nino is a well known outcome of this currents effect on weather. 

Finally, the Guinea Current is an extension of the Atlantic’s Equatorial Counter -Current.

Cold Ocean Currents

Cold Arctic waters that move south into the Atlantic are called the East Greenland Current.  The Labrador Current  containing cold water and icebergs flows south meeting the Gulf Stream off the U.S. coast.  The Humboldt Current is cold water from Antarctica that flows northeastward into the South Pacific off the coast of Peru. 

The Oyashio brings cold water into the Pacific from the Bering Sea.

The California Current is slow moving cold water that follows the west coast of the U.S.

The Antarctic Circumpolar Current is the strongest and fastest current of all.  It travels eastward circling the Antarctic continent at about 1/2 mile per hour.  The Benguela Currents, strong currents from Antarctica, flow northward into the South Atlantic.

The amount of water carried by the world’s water currents is enormous.  The Gulf Stream alone carries 50 to 70 times more water than all the world’s rivers put together. 

1.  Print a  a map of the U.S.      (WeatherNet Classroom allows you to print various maps for activities. This link does not work here.)

        a.  Add to the map the climatic effects on the U.S. you would expect from the currents.  Use your knowledge of wind patterns and the effects of temperature on the weather.

2.  Investigate the temperatures for several sites at several different times of the day.  As currents move past landmasses, the temperature of the currents affect the temperature of the land (see the lesson Wind).  This in turn will set up conditions that will change weather patterns and therefore the climate near the current.  Remember that the prevailing winds move from west to east across the U.S. 

On the map below, choose areas that are near bodies of water.  How does the data compare with what you have learned about the effects of ocean currents on weather patterns?

• What are the earth's ocean currents that influence weather?
• How do ocean currents affect the earth's weather?

1. Research interesting facts about ocean currents.  Keep in mind historical aspects like exploration, great sea disasters, and sail boat racing.
2. Investigate the technology involved in recording currents and their effects.
3. Check out the information available from the National Oceanic & Atmospheric Administration (NOAA).  http://www.pmel.noaa.gov/bering/pages/env_cur.html and http://fermi.jhuapl.edu/avhrr/sst.html