movements of the ocean chapter 22 22.1: ocean currents current: giant streams of water that move...

Download Movements of the Ocean Chapter 22 22.1: Ocean Currents Current: Giant streams of water that move through the ocean Examples: Gulf Stream, El Niño Surface

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  • Slide 1
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  • Movements of the Ocean Chapter 22
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  • 22.1: Ocean Currents Current: Giant streams of water that move through the ocean Examples: Gulf Stream, El Nio Surface currents: move on or near the surface of the ocean and are driven by winds Deep currents: move slowly beneath the surface due to differences in water density
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  • Factors that affect surface currents 1. Windsmovement from high pressure air towards low pressure air Trade winds: found in tropics, blow from east to west (called easterlies) North of the equator they blow from northeast South of the equator they blow from southeast Westerlies: blow from west to east in middle latitudes
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  • Moisture/Pressure Zones Low Pressure: Wet High Pressure: Dry Low Pressure: Wet High Pressure: Dry
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  • Factors that affect surface currents 2. Earths rotation: as air moves up and down, the earth rotates below it. Therefore, the air comes down west of where it went up. Coriolis effect: the deflection of the earths winds and currents due to the earths rotation Gyre: huge circular currents that are driven by wind and coriolis effect Clockwise in north, counter-clockwise in south
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  • Factors that affect surface currents Continents: water is deflected and divided when it hits continents.
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  • Equatorial Currents Equatorial currents: north and south of the equator in each ocean are warm currents flowing westward Equatorial countercurrent: warm, weak current between the equatorial currents that flows eastward.
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  • North Atlantic Gyre Gyres typically consist of four currents Weaker currents are called drifts Gulf stream (5000X bigger than the Mississippi) to North Atlantic Drift to Canary Current to North Atlantic equatorial current Sargasso Sea: relatively still water in the middle.
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  • North Pacific Gyre Japan current to North Pacific current to California Current to North Pacific equatorial current
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  • Southern Hemisphere Currents West wind drift: worlds largest current, goes through all three oceans around Antarctica
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  • Deep Currents Antarctic bottom water: coldest, saltiest, densest water is near Antarctica, it flows slowly north to about 40 latitude. Takes 100s of years North Atlantic deep water: flows south from Greenland, below the Gulf Stream but on top of Antarctic bottom water
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  • 22.2: Ocean Waves Wave: periodic up and down movement of water Crest: highest point of the wave Trough: lowest point of the wave Wave height: vertical distance between crest and trough
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  • Ocean Waves Wave length: horizontal distance between two consecutive troughs or crests Wave period: Time in seconds it takes for one complete wavelength to pass a given point. Wave speed: wave length divided by wave period
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  • Wave energy 1.Energy from the wind is transferred to the surface of the water by friction 2.Small ripples form 3.As ripple receives more energy from wind, it grows into wave 4.Longer the wind blows, more energy is transferred and the bigger the wave becomes
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  • Wave energy Swell: one of a group of long rolling waves that are all the same size
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  • Water movement in waves 1.Energy in waves moves forward, water does not 2.Water molecules move in a circular pattern 3.The diameter of the circle is equal to wave height 4.Very little movement of water at a depth equal to half the wavelength
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  • Factors Affecting Wave Size 1.Speed of the wind 2.Length of time wind blows 3.Fetch: the distance the wind can blow across open ocean Biggest waves: strong, steady winds over a long fetchtypical in storms
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  • Wave Size Limit to wave size: if the wave gets too high compared to the length (height of about length), the wave collapses Whitecaps: when high winds blow crest off the top of the wave
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  • Breakers 1.When the depth of the water is about wavelength, the wave touches bottom 2.This slows the bottom of the wave while the top keeps going 3.The top gets so far ahead that it falls over, forming a breaker 4.Height of wave when it falls is usually 1-2 times original wave height
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  • Breakers 5.Steep slopes lead to bigger breakers, common on Pacific Coast 6.Gentle slopes, waves break with a rolling motion, common on sissy Atlantic Coast
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  • Other waves Refraction: most waves approach shore at an angle then bend and approach parallel Undertow: water that breaks on beach is pulled back to sea, usually only strong on steep beaches Rip current: occur when water from large breakers flows through channels in sandbarsdetected by a gap in breakers
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  • 22.3: Tides Tide: daily changes in the level of the ocean surface, caused by moons gravitational pull on the oceans. North Pole High Tide Low Tide
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  • Moon/earth relationship 1.Earth rotates once every 24 hours 2.Moon travels 1/27 th of its orbit every day 3.Therefore, the moon is over one part of the earth every 24 hours and 50 minutes. 4.Therefore, tides are 50 minutes later each day.
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  • Tides Daily Tidal Range: difference in height between high and low tide. Sun: also affects tides, but is not as strongly as moon (its bigger but farther away)
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  • Full Moon New Moon Spring tides: occur during full/new moon when earth, sun, and moon are all in a line, increases the daily tidal range because gravitational pull of moon and sun are combined.
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  • Moon Moon Neap Tides: occur during first and third quarter moons, pull of sun and moon tend to cancel each other out so that the daily tidal range is less.
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  • Tides Tidal currents: as ocean rises and falls with tides, it flows towards or away from the coast Flood tide: tidal current towards coast Ebb tide: tidal current away from coast Slack water: time between flood and ebb tides