GEOS 212 1st Edition Lecture 18Outline of Last Lecture LECTURE 17 OUTLINE (El Nino / La Nina, Hurricanes) - Review of dynamic aspects of oceans ( keep oceans well mixed!) o -- Waves (surface layer) -- Surface currents (surface layer)o -- Longshore currents (surf zone)o -- Coastal upwelling/downwelling (deep & shallow water on local scale) o -- Density currents (driven by temperature and salinity): #1: up at the equator from sun heat, down at high latitudes, turns in 100 years! #2: Seasonal (up in summer hemisphere, down in winter hemisphere) Driven largely by formation of ice sheets in winter Produces upwelling in opposite hemisphere (controls migration patterns!) Slow (~100 year rate), and never turns in complete circle. #3 = Conveyor Belt current (mixes all oceans, turns in 1000 years) - Mixing time of the oceans = 1600 years!- Impact of mixing time on marine life and society - El Nino: o patterns, causes, and consequencesThese 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.o history back thru time o connection to global warming?- Pattern of hurricanes in profile and map view (where up/down?)- Conditions needed for hurricanes (warm water, warm unstable air, upper level winds, not on equator) \- Hurricanes, typhoons, and cyclones (same storm in different oceans) - Hazards: (storm surge to 30 feet, heavy rains over 1” per hour, strong winds >74 to >200 mph - Hurricane tracks - Relation to global warmingOutline of Current Lecture: LECTURE 18 OUTLINE (Tsunami, Tides, & Global Warming )- Hurricane Movie Time: Patterns and hazards - Hurricane intensity through time: increasing, related to global warming?- Connections to El Nino / La Nina? - Tsunami caused by up/down movement of water, most commonly earthquakes in subduction zones! - 2004 Sumatra earthquake & tsunami - 2011 earthquake & tsunami in Japan- 1700 Tsunami along the coast of Oregon-Washington and California; Next One?- Hazardous aspects of tsunami: o Travel Fast (~500 mph in deep water!) o Hard to track in deep water; Need Early Warning System (most in Pacific) o Height builds in shallow water o Many waves o First one commonly a low (water recedes) o Largest one can be any one! o Earthquake that causes tsunami can be far awayo Affects huge area or ocean margin o Rare, so people forget about hazards! - Tsunami from space impacts, volcanic eruptions - Tsunami heights for 2004 Indonesian EQ?- Evidence for large EQ/Tsunami in 1700 in Pacific NW of U.S. When will the next one happen?TIDES = another dynamic process (actually a wave) that affects all oceans - Main force = gravitational pull from the moon (creates bulge in earth) - Smaller force = gravitational pull from the sun - Earth-Moon-Sun system creates 28 day cycle: Big range = spring tides = full moon & new moon Small range = neap tides = half moon Tide chart below for 28 days: spring/neap tides full/new/half moon phases, 2 Hi & 2 Lo tides perGLOBAL WARMING: - Basics of Greenhouse affect - Carbon Dioxide in the atmosphere - Climate change - Sea Level Change Bleaching of Coral Reefs Energy use - climate change - global politics!Current
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