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Unformatted text preview: CHAPTER 16 OCEANS AND COASTLINES Five ocean basins: (1) Pacific-largest-covers 1/3 of Earth’s surface (2) Atlantic-half the surface area of the Pacific (3) Indian (4) Arctic (5) Antarctic Salinity- total quantity of dissolved salts, expressed as a percentage Dissolved salts make up 3.5% of the weight of ocean water Three distinct temperature zones in the ocean: (1) Warm layer extends from surface to a depth of 450 meters (2) Thermocline- a zone in which the temperature drops rapidly with depth-extends to a depth of 2 kilometers (3) Cold deeper layer – temp. varies from 1 to 2.5 degrees Celsius TIDES Tides- vertical displacements of water Tides are caused by the gravitational pull of the Moon and Sun on the sea surface Coastlines experience two high tides and two low tides within 24 hours and 53 minutes Spring Tides- when the sun and moon are directly in line with Earth, their gravitational fields combine to create a strong tidal bulge, variation between high and low tides is very large Neap Tides- when the moon is 90 degrees out of alignment with the Sun and Earth, each partially offsets the effect of the other and the diff between high and low tides are smaller In the central oceans, tides average about 1 meter SEA WAVES Most ocean waves develop when wind blows across water In deep water, the size of a wave depends on (1) the wind speed (2) the length of time that the wind has blown (3) the distance the wind has traveled (fetch) Crest : the highest part of a wave Trough : the lowest part of a wave Wavelength : the distance between successive crests Wave height : the vertical distance from the crest to the trough Water molecules do not travel with the wave, while the wave moves horizontally, water molecules move in small circles The circles of water movement become smaller with depth, at a depth equal to about half the wavelength, the disturbance becomes negligible STORM SURGE Storm surge : an onshore flood of water created by a low-pressure weather system such as a hurricane or tropical cyclone Caused by strong winds of a hurricane or cyclone blowing over the sea surface and causing seawater to pile up above sea level Low pressure at the center of a storm also sucks the sea surface upward to enhance the height of the water mound Highest and most damaging when they coincide with high tide Bay of Bengal on the coastlines of India and Southeast Asia known as storm surge capital of the world OCEAN CURRENTS Current : a continuous flow of water in a particular direction Surface currents : caused by wind blowing over the sea surface, flow in the upper 400 meters of the seas and involve 10 percent of the water in oceans Deep-sea currents : transport seawater both vertically and horizontally below a depth of 400 meters and are driven by gravity as denser water sinks and less dense water rises Gulf Stream : current flowing north along east coast of North America and across the Atlantic to England Ocean surface currents are driven primarily by wind Ocean currents profoundly affect Earth’s climate...
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This note was uploaded on 02/04/2011 for the course ESC 1000 taught by Professor Staff during the Fall '08 term at University of Florida.
- Fall '08