Chapter 16 The Dynamic Ocean
Section 16.1 Ocean Circulation
16.1 The Composition of Seawater Surface Circulation Ocean current is the mass of ocean water that flows from one place to another. Surface Currents • Surface currents are movements of water that flow horizontally in the upper part of the ocean’s surface. • Surface currents develop from friction between the ocean and the wind that blows across its surface.
Ocean Surface Currents Makes no sense without caption in book
16.1 The Composition of Seawater Surface Circulation Gyres • Gyres are huge circular-moving current systems that dominate the surfaces of the oceans. • The Coriolis effect is the deflection of currents away from their original course as a result of Earth’s rotation.
16.1 The Composition of Seawater Surface Circulation Ocean Currents and Climate • When currents from low-latitude regions move into higher latitudes, they transfer heat from warmer to cooler areas on Earth. • As cold water currents travel toward the equator, they help moderate the warm temperatures of adjacent land areas.
False-Colored Satellite Image of the Gulf Stream Makes no sense without caption in book
What causes ocean surface currents? Gravitational attraction Friction between the ocean and wind on its surface Ocean movements associated with earthquakes Changes in water density
Currents affect climate by Making ocean water evaporate Transferring heat and cold between the tropics and polar regions Changing the density of water in the tropics Transferring heat from the polar regions to the tropics
16.1 The Composition of Seawater Surface Circulation Upwelling • Upwelling is the rise of cold water from deeper layers to replace warmer surface water. • Upwelling brings greater concentrations of dissolved nutrients, such as nitrates and phosphates, to the ocean surface.
Effects of Upwelling Makes no sense without caption in book
16.1 The Composition of Seawater Deep-Ocean Circulation Density Currents • Density currents are vertical currents of ocean water that result from density differences among water masses. • An increase in seawater density can be caused by a decrease in temperature or an increase in salinity.
What is the importance of upwelling? It brings warm water from the tropics to the poles. It decreases winds along exposed coastlines. It helps warm the North Atlantic gyre. It brings dissolved nutrients to the ocean’s surface.
A decrease in seawater temperature or an increase in salinity causes Upwelling along tropical coast. An increase in seawater density. The circulation of ocean gyres. A decrease in seawater density.
16.1 The Composition of Seawater Deep-Ocean Circulation High Latitudes • Most water involved in deep-ocean currents begins in high latitudes at the surface. Evaporation • Density currents can also result from increased salinity of ocean water due to evaporation. Example: The Mediterranean Sea
16.1 The Composition of Seawater Deep-Ocean Circulation A Conveyor Belt • In a simplified model, ocean circulation is similar to a conveyor belt that travels from the Atlantic Ocean, through the Indian and Pacific Oceans, and back again.
Conveyor Belt Model Makes no sense without caption in book
Cross Section of the Arctic Ocean Makes no sense without caption in book
What causes density currents to form in the Mediterranean Sea? Freezing Evaporation Melting Ice Upwelling