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PART II: People and their
GEOG 101 Part II Physical Environment People and their I. Introduction to the Physical Environment Physical Environment II. Earth-Sun Relationship III. Earth Systems A. The Hydrosphere: Oceans B. The Atmosphere: Weather and Climate C. The Lithosphere: Geologic Influences IV. Earth Habitat A. Biosphere B. Natural Controls and Cycles
Lecture design, content and C. Human Impact Prof. Anthony Grande presentation ©AFG 0221 Individual images and illustrations D. Natural Hazards Hunter College Geography may be subject to prior copyright. E. Earth Resources
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HYDROSPHERE: Overview HYDROLOGIC CYCLE
• Earth is the Water Planet: 71% of surface is water and 97% of all water is in the oceans. • Ocean Movements: The oceans are a dynamic system with much activity and interactions. • Water Temperature and Climate: Surface ocean temperatures affect air temperature and therefore climate. • Oceans play an important The “Hydrologic Cycle” explains how the earth maintains and cleans Oceans and People: its water supply, constantly producing new fresh water. The oceans, role in earth environment, influencing many things containing over 97% of the water found on Planet Earth, are the chief source of atmospheric moisture. people do. https://www.youtube.com/watch?v=vP4QTyVQTUo 2 min oceans video More on this in the lectures on the atmosphere and biosphere. 3 4
OCEAN BASIN THE DYNAMIC OCEAN TOPOGRAPHY The movements found in the ocean are a result of numerous aspects of fluid dynamics working together, transferring energy and creating motion.
Ocean current: a ribbon (or Wave: a friction-generated river) of moving sea water with phenomena created as wind The ocean floor unique characteristics. passes over and touches the Gyre: a giant circulation sys- surface of water, dragging it is not flat! forward, creating a crest. tem found both on the surface of the oceans and in the atmos- Tsunami: a seismic sea phere; caused by the earth’s wave created by a shock More on the ocean rotation and the Coriolis Effect. (falsely called a tidal wave). basin when we do the Ocean gyre: a system of Tide: a moving bulge of water geology section. circular ocean currents. created the moon’s gravitation- al pull and by earth's rotation. 5 6
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MOVEMENTS Gyre: giant circulation system linked to rotation and Coriolis. MOVEMENTS in the OCEAN in the OCEAN Ocean gyre is a large system of circular ocean currents formed Ocean current: A ribbon by global wind patterns, Earth's Waves (wind waves) are Tides (moving water bulges) (or river) of moving sea rotation and the Coriolis Effect. generated mainly by the are caused by the gravita- water, with unique charact- The world’s five ocean gyres help transfer of energy from tional pull of the moon and eristics, generated by the to drive the oceanic conveyor belt wind to water by friction. sun and by the earth's earth's rotation and by that circulates ocean water around Waves help to mix water of dif- rotation. the differences in water the planet. ferent temperature and salinity. . Tidal bore (the true tidal salinity and water Waves alter the coastline by wave) is the leading edge temperature. erosion and deposition. of the incoming or high Ocean current Tsunamis are seismic sea tide, esp. evident when movements are waves (not tidal waves). approaching shallow water. both horizontal They are generated by earth- (surface) and ver- . Tidal range is the differ- quakes, underwater land- ence in height between tical (deep sea). slides and any other shock inducer that transfers energy. high and low tide. 7 8
Simplified Ocean Salinity Map SURFACE OCEAN CIRCULATION KEY
Note the areas of very high salinity and low salinity on the map.
C A
The diagram below shows B how salinity varies with environmental conditions. C
A. The Mediterranean Sea is getting more salty because of freshwater diversion by people. B. The Arabian Sea has high salinity because it has hot, desert conditions. C. The two Atlantic Ocean zones have high rates of water evaporation. Currents are designated warm and cold by their source region, not their temperature. Surface currents influence climate on land https://www.youtube.com/watch?v=5xQP_B18vMw through the transfer of temperature and moisture characteristics. 3 min video on ocean water salinity 9 10
It crosses the Atlantic Ocean as the DEEP‐SEA OCEAN Gulf Stream North Atlantic Drift (D), warming the atmosphere and bringing warmth and System moisture to NW Europe. As the warm CURRENTS ocean surface water evaporates, it E makes the underlying water saltier and therefore, denser, before being D cooled by the Arctic Ocean (E). The chilled saline water sinks and then Thermo = heat C begins a return-journey back south as Haline = salinity Differences in temper- a cold, deep-water current (blue line). ature and salt content B create density gradi- ents that generate movements. A What happens if something interferes with this system? The Gulf Stream (red line) starts as the Atlantic North Equatorial (A). It carries A giant meteor strikes the ocean tropical water north along the coast of between Great Britain and Iceland. South America and into the Caribbean Something slows the speed of flow Sea (B). It continues northward along the between N. America and Europe. coasts of Florida, Georgia and North The current’s surface temperature Thermohaline circulation https://www.youtube.com/watch?v=jOVvXDI0KbY Carolina before being deflected eastward or salt content changes. 3 min No sound 11 at Cape Hatteras (C). 12
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5. The “wave swells” grow in height until they reach a point beyond which they cannot support WAVE What if the Gulf Stream Weakens? themselves (orbit collapses) and the “swells break apart and crash” creating breakers. FORMATION
1. Swells are created by wind friction
“The Cold Blob” What happens to Europe? What happens 3. Wave energy is along the east 7. SURF ZONE 6. “Broken” 4. Maximum 2. Wave affected by prox- coast of the U.S.? After the waves break, wave swells steepness of energy from turbulent water (surf) (breakers) orbit occurs imity to the sea swells in deep What happens floor and in shallow runs up the shore (swash) create the before the sea water is to the global water wave orbits thermohaline and then flows back to surf zone. wave breaks. contained with- slant shoreward; in a circular circulation the basin (backwash). The warming of the atmosphere is cooling system? orbits become orbital motion. the North Atlantic Ocean! How can this be? oval-shaped. Can you see the scenario from the map? Most waves are wind generated. Friction Breaking waves Remember, everything on earth is interrelated. from the bottom of an air mass moving against in the surf zone Read the article and view the animation from the link: the top of the water causes the water to move constantly shape https://www.nytimes.com/interactive/2021/03/02/climate/atlantic-ocean-climate- 13 14 change.html?smid=url-share in orbits and pile on top of itself creating swells. the shoreline.
TSUNAMI: A shock‐generated ocean wave Tsunamis and the Ocean Floor The physics CAUSES: behind a • Earthquake tsunami wave • Landslide • Meteor strike
Sendai, Japan (2011) before and after being hit by the tsunami. https://www.youtube.com/watch?v=Slw ZzbGh7Cw earthquake tsunami 3D demo 1 min In deep water the wave is barely noticeable. no sound In shallow water the wave grows in height https://www.youtube.com/watch?v=Kst QogN8DUA NOAA Hawaii landslide proportional to its length, similar to a flat piece tsunami scenario, animation, 2 min of paper being pressed against a hard object. https://www.youtube.com/watch?v=mD Also, note that the wave crests are closer to f6zELkDHk Small tsunami, Indonesia, each other in shallow water producing numer- Jan. 2018, 2 min ous “wave hits” against the shoreline within a 15 short period of time. 16
OCEANS and They are used for: . transportation PEOPLE . drinking water through N E X T Oceans help to equalize desalinization process the Earth's temperature. . recreation THE ATMOSPHERE: They are the chief source . waste disposal of atmospheric moisture. Plastic debris caught in Aspects of Weather and Climate They are an important link gyre circulation systems. in the carbon/oxygen cycle. They are a source of food. https://www.nytimes.com/2019/02/28/climate/fish-climate- change.html?login=email&auth=login-email They are a source of They are a major barrier to minerals. interaction. Their rise and fall effects Historically ocean coasts coastline habitation. have been the gateway to cultural interaction. 17 18
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