GEOL 102 1st Edition Lecture 15 Outline of Last Lecture I. Mass MovementsII. Setting the Stage for Mass MovementsOutline of Current Lecture I. IntroII. Currents III. TidesCurrent LectureI. Intro60% of the global population lives within coastal regionsAverage rates of coastal erosion in CA are 15-75 cm/yrRate of sea level rise is 2-3 mm/yr and projected to speed upWhy does water move in oceans?WindsHeat (via solar radiation)GravityII. CurrentsCoriolis forces deflect flows:To the right in the Northern HemisphereTo the left in the Southern hemisphereSurface CurrentsFlowing or circulating waterThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Result from wind shearMovement is not parallel to wind directionHeat redistributionCurrents are deflected ~90* from the wind directionSurface Circulation PatternsGyres: large circular flow patternsNorthern hemisphere: clockwiseSouthern hemisphere: counterclockwise Deep-water currents are driven by:Upwelling and downwelling along coastsThermohaline circulation: temperature and salinity related to densityIII. TidesDaily cycles of local sea level fluctuationsShoreline position changesWave-like bulged in ocean surface due to gravitational pull of the sun and the moonGravitational pull varies with the size and distance of objectsMost areas have two daily tidesMoon’s influence is larger than the sun’s (twice)Side of Earth facing the moon feels the strongest pullSide of Earth on opposite to moon feels less pullWater surface is ellipticalVariations are due to:Tilt of Earth’s axisMoon’s orbitShape of bays and coastsTidal range (reach):Vertical difference between low and high tideDepends on size of water body and shape of coastsSpring tides occur when the earth, sun, and moon are alignedNeap tides occur when the Earth is the corner of a 90* angle made by the sun and moonTides can reverse the flow of
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