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Transcript
Chapter 5 Ecosystems and the Physical Environment Overview of Chapter 5 o o o o o o Biogeochemical Cycles Solar Radiation The Atmosphere The Global Ocean Weather and Climate Internal Planetary Processes Biogeochemical Cycles Matter moves between ecosystems, biotic & abiotic environments, and organisms • Unlike energy Biogeochemical cycling involves • Biological, geologic and chemical interactions Five major cycles: • Carbon, Nitrogen, Phosphorus, Sulfur and Water (hydrologic) The Carbon Cycle Cycling of Materials within Ecosystems Nitrogen cycle: Biological nitrogen fixation NH3 & NH4- Atmospheric nitrogen (N2) Nitrogen fixation by humans Decomposition Internal cycling Nitrification Denitrification Plant & animal proteins Assimilation NO3 - The Nitrogen Cycle Cycling of Materials within Ecosystems Phosphorus cycle: Phosphate rocks Excretion / decomposition Phosphate mining Erosion Internal cycling Marine organisms Marine sediments Fertilizer containing phosphates Dissolved phosphates Erosion Animals, crops Internal cycling Soil phosphates The Phosphorus Cycle The Sulfur Cycle The Water (Hydrologic) Cycle Solar Radiation Sun provides energy for life, powers biogeochemical cycles, and determines climate 69% of incoming solar radiation is absorbed by atmosphere and earth • What happens to the rest? Albedo • • The reflectance of solar energy off earth’s surface Dark colors = ??? • • Forests and ocean Light colors = ??? • Ice caps, glaciers, snow Temperature Changes with Latitude Solar energy does not hit earth uniformly • Due to earth’s spherical shape and tilt Equator (a) Closer to Poles (c) High concentration Little Reflection High Temperature Low concentration Higher Reflection Low Temperature Temperature Changes with Season Seasons determined by earth’s tilt (23.5°) Causes each hemisphere to tilt toward the sun for half the year Northern Hemisphere tilts towards the sun from March 21- September 22 (warm season) The Atmosphere Invisible layer of gases that envelopes earth Content • • • 78% Nitrogen 21% Oxygen 1% Argon, Carbon dioxide, H2O, Neon and Helium Density decreases with distance from earth Shields earth from high energy radiation Atmospheric Layers Exosphere (500km and up) • • Outermost layer Atmosphere continues to thin until converges with interplanetary space Thermosphere (80-500km) • • Gases in thin air absorb x-rays and short-wave UV radiation = very hot Source of aurora Atmospheric Layers Mesosphere (45-80km) • Temperature decreases with altitude Stratosphere (10-45km) • • Temperature increases with altitude- very stable Ozone layer absorbs UV Troposphere (0-10km) • • Where weather occurs Temperature decreases with altitude Atmospheric Circulation Near Equator • • • Warm air rises, cools and splits to flow towards the poles ~30°N&S sinks back to surface Air moves along surface back towards equator This occurs at higher latitudes as well • Moves heat from equator to the poles Surface Winds Winds blow from high to low pressure Large winds due in part to pressures caused by global circulation of air High Low High Low High Low High Coriolis Effect Earth’s rotation influences direction of wind • • Earth rotates from East to West Deflects wind from straight-line path Coriolis Effect • • • Influence of the earth’s rotation on movement of air and fluids Turns them Right in the Northern Hemisphere Turns them Left in the Southern Hemisphere Coriolis Effect Visualize it as a Merry-Go-Round (see below) Global Ocean Circulation Prevailing winds produce ocean currents and generate gyres Example: the North Atlantic Ocean • • • Trade winds blow west Westerlies blow east Creates a clockwise gyre in the North Atlantic Circular pattern influenced by coriolis effect Global Ocean Circulation Westerlies Trade winds Position of Landmasses Large landmasses in the Northern Hemisphere help to dictate ocean currents and flow Very little land in the Southern Hemisphere Vertical Mixing of Ocean Ocean Interaction with AtmosphereENSO El Niño-Southern Oscillation (ENSO) • Def: periodic large scale warming of surface waters of tropical eastern Pacific Ocean Alters ocean and atmospheric circulation patterns Normal conditions- westward blowing tradewinds keep warmest water in western Pacific Ocean Interaction with AtmosphereENSO ENSO conditionstrade winds weaken and warm water expands eastward to South America • Big effect on fishing industry off South America ENSO Climate Patterns Weather and Climate Weather • • The conditions in the atmosphere at a given place and time Temperature, precipitation, cloudiness, etc. Climate • • • The average weather conditions that occur in a place over a period of years 2 most important factors: temperature and precipitation Earth has many climates Weather and Climate Precipitation: • Atacama Desert in Chile = 0.05 cm / year • Mount Waialeale in Hawaii = 1200 cm / year • What is the annual precipitation in your area? • Kaiserslautern gets nearly 100cm a year. Rain Shadows Mountains force humid air to rise Air cools with altitude, clouds form and precipitation occurs (windward side) Dry air mass moves down opposite leeward side of mountain Severe Weather Events: Tornadoes Powerful funnel of air associated with a severe thunderstorm Formation: • • • Mass of cool dry air collides with warm humid air Produces a strong updraft of spinning air under a cloud Spinning funnel becomes tornado when it descends from cloud Wind velocity= up to 300mph Width ranges from 1m to 3.2km Tornadoes Frequency of tornados annually per 100,000 km2 Tornado Alley (US) 40 Sydney, Australia 8 United Kingdom 1 Bangledesh 0.6 Severe Weather Events: Tropical Cyclones Giant rotating tropical storms Wind >119km per hour Formation • • • Strong winds pick up moisture over warm surface waters Starts to spin due to Earth’s rotation Spin causes upward spiral of clouds Damaging on land • • High winds Storm surges Severe Weather Events: Tropical Cyclones Tropical cyclones Atlantic Ocean = hurricanes Pacific Ocean = typhoons Indian Ocean = cyclones Internal Planetary Processes Layers of the earth • Lithosphere • • Outermost rigid rock layer composed of plates Asthenosphere • Lower mantle comprised of hot soft rock Plate Tectonics- study of the processes by which the lithospheric plates move over the asthenosphere Plate Boundary- where 2 plates meet • Common site of earthquakes and volcanoes Plates and Plate Boundaries Internal Planetary Processes Volcanoes Most volcanoes occur along subduction zones Internal Planetary Processes Volcanoes Some occur along spreading zones Few, such as Hawaiian Islands, not associated with plates. Types of Plate Boundaries Divergent Plate Boundary-2 plates move apart Convergent Plate Boundary-2 plates move together (may get subduction) Types of Plate Boundaries Transform Plate BoundaryTwo plates move horizontally in opposite, parallel directions Earthquakes Caused by the release of accumulated energy as rocks in the lithosphere suddenly shift or break • • Occur along faults Energy released as seismic wave Focus- the site where the earthquake originates below the surface Epicenter- located on the earth’s surface, directly above the focus Richter scale and the moment magnitude scales are used to measure the magnitude Tsunami Giant undersea wave caused by an earthquake, volcanic eruption or landslide • Travel > 450mph Tsunami wave may be 1m deep in ocean • Becomes 30.5m high on shore Magnitude 9.3 earthquake in Indian Ocean • Triggered tsunami that killed over 230,000 people in South Asia and Africa