movements of the ocean
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DESCRIPTIONMovements of the Ocean. Chapter 21. Ocean Currents. Current : a horizontal movement of water in a well-defined pattern, such as a river or stream. 1. Surface Current : a horizontal movement of ocean water that is caused by wind and occurs at or near the ocean’s surface. - PowerPoint PPT Presentation
Movements of the OceanChapter 21
Ocean CurrentsCurrent: a horizontal movement of water in a well-defined pattern, such as a river or stream.
1. Surface Current: a horizontal movement of ocean water that is caused by wind and occurs at or near the oceans surface.
2. Deep Current: a streamlike movement of ocean water far below the surface that is denser and colder.
Surface CurrentsFactors that Affect Surface Currents.1. Air Currents (wind)2. Earths Rotation 3. The Location of the Continents
Global Wind BeltsTrade Winds: are located just north and south of the equator. In the Northern Hemisphere trade winds blow from the northeast. In the Southern Hemisphere they blow from the southeast.
Westerlies: are located in the middle latitudes. In the Northern Hemisphere they blow from the southwest and in the Southern Hemisphere they blow from the northwest.
Global Wind Belts
Continental BarriersThe continents act as barriers to surface currents. When a surface current flows against a continent, the current is deflected and divided.
Earths RotationCoriolis Effect: the apparent curving of the path of a moving object from an otherwise straight path due to Earths rotation.
Gyre: a huge circle of moving ocean water found above and below the equator. In the Northern Hemisphere water flow in gyres is to the right and in Southern Hemisphere water flows to the left, counterclockwise.
Major Surface CurrentsEquatorial Currents: warm currents that flow in a westward direction.
Antarctic Circumpolar Current: is the current that completely circles Antarctica and crosses all 3 major oceans.
Major Surface CurrentsGulf Stream: the swift, deep, and warm Atlantic current that flows along the eastern coast of the United States toward the north.
Deep CurrentsDeep Currents: are colder, slower, and denser currents far below the surface. Deep currents form as cold, dense water of the polar regions sinks and flows beneath warmer ocean water.
Turbidity CurrentsTurbidity Currents: is a strong current caused by an underwater landslide. The turbid waters are more dense and therefore move beneath the less dense clear water.
Ocean WavesWave: a periodic disturbance in a solid, liquid, or gas energy is transmitted through a medium. Ocean waves are periodic up and down movements of water.
Ocean WavesCrest: is the highest point of a wave.
Trough: is the lowest point between two crests.
Ocean WavesWave Height: is the vertical distance between the crest and trough of a wave.
Wavelength: is the horizontal distance between 2 consecutive crests or between 2 consecutive troughs.
Ocean WavesWave Period: the time required for 2 consecutive wave crests to pass a given point.
Wave Speed: the speed at which a wave moves is calculated by dividing the waves wavelength by its period.
Water Movement in a WaveWater Movement in a Wave: as a wave moves across the surface of the ocean, only the energy of the wave, not the water, moves in the direction of the wave. The water molecules move in a circular motion.
Wave Energy is caused by wind.
Wave SizeThree Factors Determine the Size of a Wave: Speed of the wind, the length of time the wind blows, and fetch.
Fetch: is the distance that wind blows across an area of the sea to generate waves.
Wave SizeLarge Waves: are produced by strong steady wind.
Choppy Waves: are produced by strong gusty winds.
Wave SizeSwell: a group of long, rolling waves that are similar in size.
Whitecaps: when winds blow the crest off.
BreakersBreakers: As a wave nears the coastline, wave height increases and wavelength decreases causing the top of the wave to topple over and form a foamy mass of water that washes onto the coastline.
RefractionRefraction: the process by which ocean waves bend directly toward the coastline as they approach shallow water, the part of the wave that is traveling in shallow water travels more slowly that the part of wave that is still advancing in deeper water.
Undertows: water carried onto a beach by breaking waves is pulled back into deeper water by gravity.
Rip Current: form when water from large breakers returns to the ocean through channels that cut through underwater sandbars that are parallel to the beach.
TidesTide: the periodic rise and fall of the water level in the oceans and other large bodies of water
Tides form because the gravitational pull of the moon decreases with distance from the moon. Because of Earths rotation, most locations in the ocean have 2 high tides and 2 low tides daily.
TidesTidal Range: the difference in levels of ocean water at high tide and low tide.
Because the moon rises about 50 minutes later each day, the times of high and low tides are about 50 minutes later each day.
Spring TidesSpring Tides: During new moon and the full moon, Earth, the sun, and the moon are aligned causing the combined gravitational pull of the sun and the moon results in higher high tides.
Neap TidesNeap Tides: During the first and third quarter phases of the moon, the moon and sun are at right angles to each other in relation to Earth causing the gravitational forces of the sun and moon to work against each other resulting in small tidal range.
Spring vs Neap Tides
Tidal OscillationTidal Oscillation: the slow, rocking motion of ocean water that occurs as the tidal bulges move around the ocean basins.
Tidal CurrentTidal Current: the movement of water toward and away from the coast as a result of the rise and fall of the tides.
Red TidesRed Tides: (algal blooms) is when large concentrations of aquatic microorganisms (phytoplankton) accumulate rapidly in the water and result in discoloration of the surface water.