World Geography 3200

Unit 2: Patterns in Weather & Climate

Chapter 4 Weather and Climate

2.4 Ocean Currents Ocean currents: Permanent or semi-permanent horizontal movement of surface water (the top 100m). It is unusually cold or hot, when compared with the surrounding water. Caused by and shaped by: Prevailing winds Variations in temperature (i.e. density of water) Coriolis effect.

Cold ocean currents move water towards the equator. The Humbolt (Peru) current carries cold water from Antarctica toward the equator. The Labrador current carries cold water from the arctic ocean toward Newfoundland. Warm ocean currents move water away from warm equatorial regions. The Gulf Stream moves warm water from the Gulf of Mexico northeast toward England. The Japanese current moves warm water from Japan northeast towards Vancouver.

Humboldt Current

Labrador Current

Ocean Currents & the Effect on Climate Affect of cold ocean currents 1. Cools the summer temperature; 2. Reduces precipitation; cooler air holds less moisture. It is drier Affect of warm ocean currents 1. Warms the winter temperature; 2. Increases precipitation; warmer air holds more moisture.

Practical Examples Mary’s Harbour on the coast of Labrador is affected by the Labrador current. It gives Mary's Harbour cool summer temperatures and surprising little precipitation for a location right on the oceans edge. Brazilia is a city in Brazil and is affected by the Brazil Current. This gives Brazilia high precipitation. The precipitation is further increased by the fact that the southeast trade winds blow off the warm ocean current onto the land. Brazilia is located within the tropics so the degree of season is very limited anyway.

Mary’s Harbour

Brazilia

Newfoundland's south coast has ice-free ports year-long while its north coast has heavy ice for several months. The difference in latitude is not enough to explain this difference in ice. Can you explain it with ocean currents?

Southcoast vs Northcoast of NL