Ocean Notes PDF

Ocean Notes  Origin of the Oceans Scientists hypothesize that Earth’s water originated from 1 either a remote source or a local source, or both. Comets and meteorites are two remote sources that could 2 have contributed to the accumulation of water on Earth. An episode o...

Ocean Notes  Origin of the Oceans Scientists hypothesize that Earth’s water originated from 1 either a remote source or a local source, or both. Comets and meteorites are two remote sources that could 2 have contributed to the accumulation of water on Earth. An episode of volcanism released large quantities of water 3 vapor and other gases into the atmosphere. The water vapor eventually condensed into oceans.  Distribution of Earth’s water The oceans contain 97 percent of the water found on Earth. 3 percent is freshwater located in the frozen ice caps of Greenland and Antarctica and in rivers, lakes, and underground sources. The northern hemisphere is covered by slightly more water than land. The southern hemisphere, however, is almost completely covered by water.  Sea Level Sea level, which is the level of the oceans’ surfaces, has risen and fallen over time in response to melting ice during warm periods and expanding glaciers during ice ages. Sea level is also affected by tectonic forces that lift or lower portions of Earth’s crust. Scientists hypothesize that this rise in sea level is related to water released by the melting of glaciers due to global warming.  Ocean and Atmosphere Interaction 1 Oceans are a source of 2 Oceans are also a vast reservoir 3 Oceans provide moisture and heat atmospheric of carbon to the atmosphere oxygen. dioxide. and influence large-scale circulation patterns.  Chemical Composition of Seawater Salinity is the measure of the amount of dissolved salts in seawater. Seawater is more dense than freshwater, and its density increases with salinity. Estuaries are an area of water that have the lowest salinity and often occurs where large rivers empty into the oceans.  Ocean Movements  Waves A wave is a rhythmic movement that carries energy through space or matter. Ocean waves are generated mainly by wind blowing over the water’s surface. The highest point of a wave is the crest and the lowest point is the trough. Collapsing waves are called breakers. A breaker forms when waveLENGTH decreases and wave HEIGHT increases as the wave nears the shore.  Tides Tides are the periodic rise and fall of sea level. The highest level to which water regularly rises is known as high tide, and the lowest level is called low tide.  Influence on Tides The gravitational forces of the sun and the moon influence the size of the tides. Lunar tides are more than twice as high as those caused by the Sun because the Moon is much closer to Earth. Spring tides are high tides that are higher than normal and low tides to be lower than normal. This occurs during a full or new moon, the Sun, the Moon, and Earth are all aligned. A neap tide occurs when the Sun, the Moon, and Earth form a right angle. When this occurs, it causes high tides to be lower and low tides to be higher than normal.  Currents Surface currents are wind-driven movements of ocean water that primarily affect the upper few hundred meters of the ocean. Surface currents follow predictable patterns and are driven by Earth’s global wind systems. Gyres are closed current circuits caused by the continents deflecting ocean currents to the north and the south.  Ocean Movements Upwelling is the upward motion of ocean water. Upwelling occurs when surface water is moved offshore and deep, colder water rises to the surface to replace it.