Presentation on theme: "CH 16 The Dynamic Ocean Ocean water is in constant motion and powered by many forces Forces include wind, Coriolis, gravity, density differences Ocean."— Presentation transcript:
1 CH 16 The Dynamic OceanOcean water is in constant motion and powered by many forcesForces include wind, Coriolis, gravity, density differencesOcean currents are masses of ocean water that flow from one place to anotherSurface or deep
2 Surface Currents Movements of water that flow horizontally Develop from wind frictionGyres = huge circular moving current systems (5)Coriolis Effect = the deflection of currents to the right in the NH (& left in the SH) due to earth’s rotationWarm currents move from the equator to the polesCold currents move from polar regions to the equatorCold currents = west coast; warm currents = east coast
3 Deep Ocean Circulation Vertical movement of waterUpwelling = cold water rising from deep layers to replace warm surface waterBrings nutrients to surface(good for fishing)Density currents = vertical currents of water due to density differencesFrom temperature(cold) and salinity (high)Read pages 451 – 453
4 Waves Most waves obtain their energy and motion from wind Big wind = big wavesCrest = topTrough = bottomWave height = distance from trough up to crestWavelength = distance from crest to next crestWave period = time it takes a full wavelength to pass a fixed position
5 Height, length, & period of waves depends on 3 factors: 1. Wind speed2. Length of time the wind blows3. Fetch (distance across body of water)The only thing that really moves forward in a wave is energy(particles move in circular orbital motion)Breakers--Waves that break (fall forward) when the depth of the water is one-half of the wavelength.
6 TIDESTides are daily changes in the elevation of the ocean due to the gravitational attraction of the moon & sun.Most places have 2 high & 2 low tides each day.Tidal Range=difference in height of high & low tide.
7 2 TIDE TYPES & 3 TIDE PATTERNS SPRING= full & new moon, largest tidal range, moon-earth-sun are all in a straight line.NEAP= 1st & 3rd quarter moons, smallest tidal range, moon-earth-sun at 90 degree angles.3 TIDE PATTERNS: (read about them)diurnal = 1 hi & 1 low per daysemi-diurnal = 2 hi & 2 lo per day (fairly equal)mixed = 2 hi & 2 lo per day (unequal)
8 SHORELINE PROCESSES/FEATURES BEACH=accumulation of sediment along shores. (white,pink,tan,black,green)SHORELINE (WAVE) FORCES:ErodingTransportingDepositingWave impactAbrasionRefraction = bending of waves
9 Wave energy is concentrated at headlands = more erosion Wave energy is weakened in bays = more depositionLongshore current = sediments carried along (parallel) to shore due to waves hitting at an angle.
10 EROSIONAL FEATURES: Sea Cliff – result from waves cutting at the base Sea Cave – from softer rock being erodedSea Arch – cave all the way throughSea Stacks – roof of the arch collapsesWave-cut platform or terrace – from continued wave action causing a flat eroded area
11 DEPOSITIONAL FEATURES: Spit – elongated ridge of sand sticking into the bayHook – when the spit hooks due to currentsBaymouth Bar – when a sand bar completely crosses the bayTombolo – a ridge of sand that connects an island to the mainlandBarrier Islands = (Outer Banks)
12 Stabilizing/protecting shores: Jetties or groins –barrier built at right angles to the beach to catch sandBreakwaters – offshore and parallel to coastSeawalls – parallel to coast often from the shoreBeach nourishmentsNatural protectors: sand bars, sand dunes, fringing reefs, barrier reefs, & atolls