Oceans Surface Currents

Wind Creation The sun heats the Earth’s atmosphere unevenly, creating very warm, low-pressure areas around the equator, and cool, high pressure areas toward the poles. As the warm air moves to high pressure areas, wind is created. Uninterrupted, wind patterns would run in straight lines from pole to pole.

What are surface currents? Surface currents are horizontal, streamline movements of water that occur at or near the surface of the ocean. Surface currents can reach depths of several hundred meters and lengths of several thousand kilometers, and can travel across oceans.

Surface current formation As wind blows across the ocean, it drags water along with it creating strong currents. Because the wind’s reach is limited, these surface currents only run about 200 meters (656 feet) deep. Short lived winds create temporary surface currents. Constant winds create more permanent currents that flow strongly on a fixed course.

What controls surface currents? 1. Global Winds 2. Coriolis Effect 3. Continental Deflection

What factors contribute to surface current formation? 1. Global Winds- winds that blow across the Earth’s surface create surface currents. They act as a heat transfer system. Global winds are due to the unequal heating of earths surface.

2. The Coriolis Effect – the apparent curving of moving objects from a straight path due to the Earth’s rotation. Because of the Earth’s rotation wind is forced right or left, depending on the hemisphere it is in.

3. Continental Deflection – when surface currents meet a continent it deflects the movement of the current. Currents change directions by hitting the continents or landmasses The Gulf Stream deflects off the coast of North America and flows across the ocean to the British Isles. As a result, the British Isles have a milder climate than Canada.

Why are some surface currents cold and others are warm? Warm water surface currents originate in the tropics and flow north and south from the equator. As the water moves farther north it cools and sinks. The colder water on the surface then moves north or south from the poles and warms as it gets closer to the tropics.

California current along the coast of California is a cold water current, causing cooler water temperatures. It originates in the poles and travels towards the tropics/equator

The Gulf Stream is a warm water current that, causing warmer water temperatures. It originates from the tropic/equator and travel towards the poles

Gulf Stream current.

Currents and Climates Surface currents gently cool or warm the coastal areas year round Some surface currents change their circulation pattern causing changes in the atmosphere that affect the climate in many parts of the world.

Warm Water Currents and Climates Warm water currents create warmer climates in coastal areas.

Cold Water Currents and Climates Cold water current bring cooler climates into areas.