Ocean Currents

1. Ocean Currents By: Cathy Jones, Beth Kuhns, and Christine Pettit

2. Ocean Currents • Ocean currents = organized flows that persist over some geographical region and over some time period such that water is transported from one part of the ocean to another part of the ocean. • There are two types: - Surface Currents--Surface Circulation - Deep Water Currents--Thermohaline Circulation

3. Surface Currents--Surface Circulation • Surface currents develop from friction between the ocean and the wind that blow across the surface • These waters make up about 10% of all the water in the ocean. • These waters are the upper 400 meters of the ocean.

4. Examples of Warm and Cold Currents Cold Currents • North Atlantic Current • Alaska Current • Peru Current • Falkland Current • Oyashio Current • Benguela Current Warm Currents • Gulf Stream • North Equatorial Current • South Equatorial Current • Brazil Current • Agulhas Current • California Current

5. Deep Water Currents--Thermohaline Circulation • These waters make up the other 90% of the ocean • These waters move around the ocean basins by density driven forces and gravity. • The density difference is a function of different temperatures and salinity • These deep waters sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase. • Deep water circulation runs the "conveyor belt" that moves warm water away from the equator and cold water away from the poles.

6. Currents Effects on Climate • Currents from low latitudes into higher latitudes (warm currents) transfer heat from warmer to cooler areas • Influence of cold currents is most pronounced in the tropics or during the summer months in the middle latitudes

7. Coriolis Effect • Since the globe is rotating, any movement on the Northern hemisphere is diverted to the right, if we look at it from our own position on the ground.

8. The Coriolis effect has great significance in astrophysics and stellar dynamics, in which it is a controlling factor in the directions of rotation of sunspots.

9. It is also significant in the earth sciences, especially meteorology, physical geology, and oceanography, in that the Earth is a rotating frame of reference, and motions over the surface of the Earth are subject to acceleration from the force indicated.

10. The Coriolis effect is most apparent in the path of an object moving longitudinally. On the Earth an object that moves along a north-south path, or longitudinal line, will undergo apparent deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

11. The Coriolis deflection is therefore related to the motion of the object, the motion of the Earth, and the latitude. For this reason, the magnitude of the effect is given by 2 sin , in which is the velocity of the object, is the angular velocity of the Earth, and is the latitude.

12. Thus, the Coriolis force figures prominently in studies of the dynamics of the atmosphere, in which it affects prevailing winds and the rotation of storms, and in the hydrosphere, in which it affects the rotation of the oceanic currents

13. Biomes Because of the Coriolis Effect and Ocean Currents, the planet has biomes • There are 5 major biomes: • Aquatic • Deserts • Forests • Grasslands • Tundra

14. Water is the common link among the five biomes and it makes up the largest part of the biosphere, covering nearly 75% of the Earth’s surface. Aquatic regions house numerous species of plants and animals, both large and small. In fact, this is where life began billions of years ago when amino acids first started to come together. Without water, most life forms would be unable to sustain themselves The aquatic biome can be broken down into two basic regions, freshwater (i.e, ponds and rivers) and marine (i.e, oceans and estuaries). Aquatic

15. Deserts • Deserts cover about one fifth of the Earth’s surface and occur where rainfall is less than 50 cm/year. Although most deserts, such as the Sahara of North Africa and the deserts of the southwestern U.S., Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia. Most deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals.

16. Today, forests occupy approximately one-third of Earth’s land area, account for over two-thirds of the leaf area of land plants, and contain about 70% of carbon present in living things. Present-day forest biomes, biological communities that are dominated by trees and other woody vegetation can be classified according to numerous characteristics, with seasonality being the most widely used. Distinct forest types also occur within each of these broad groups.There are three major types of forests, classed according to latitude: tropical temperate boreal forests (taiga) Forests

17. Grasslands are characterized as lands dominated by grasses rather than large shrubs or trees. There are two main divisions of grasslands: (1) tropical grasslands, called savannas, and (2) temperate grasslands Grasslands

18. Tundra • Characteristics of Tundra • Extremely cold climate • Low biotic diversity • Simple vegetation structure • Limitation of drainage • Short season of growth and reproduction • Energy and nutrients in the form of dead organic material

19. Work Consulted • www.webct.udayton.edu • www.enature.com