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The Dynamic Earth Chapter 3 Environmental Science Earth •An integrated system containing four interacting parts: –The Geosphere –The Atmosphere –The hydrosphere –The biosphere Section 1- Geosphere •The solid part of the earth that contains all rock, soils and sediments of Earth’s surface. •At the equator the distance from crust to crust is about 12,756 km. The Atmosphere •Mixture of gases that make up the air we breath. •Nearly all found in the first 30km above the Earth’s surface. The Hydrosphere •All of the water on or near Earth’s surface. •Covers nearly 75% of the surface. •Found in atmosphere, land and soil. The Biosphere • Made up of parts of the atmosphere, hydrosphere and geosphere. • The part of Earth where life exists. • Extends 9km above Earth’s surface to the bottom of the oceans. Dividing Earth • Earth can be divided into three compositional layers: – Crust=thin outer layer, least dense, made of light elements,1% of mass. – Mantle=64% of mass, rocks of medium density, layer below crust. – Core=densest elements, approximately 3400km radius. Structure of Earth •Five physical layers: – Lithosphere= outer layer, cool, rigid, divided into huge pieces called tectonic plates. – Asthenosphere= flowing, plastic, solid layer that allows the tec. plates to move Structure continued… – Mesosphere= lower part of the mantle. – Outer core= liquid, nickel and iron. – Inner core= solid, nickel and iron Plate Tectonics •Major plates include the Pacific, North American, South American, Eurasian, and Antarctic. •Move around on the asthenosphere like ice on water. Geologic Activity • Most of the geologic activity takes place at the boundaries between tectonic plates: – Mountain building=push together. Himalaya Mountains still growing. – Earth quakes=collide, slip past or pull apart from each other. Measured by the Richter scale. Magnitude 2= smallest to be felt, 9.5=largest recorded. – Volcanoes=mountain built from magma. Can form islands. – Erosion=removal and transport of surface material. Types=wind and water. Section 2- The Atmosphere •The mixture of gases that surround Earth. – Nitrogen (78%), oxygen (21%), carbon dioxide, and other gases (1%). – Constantly changing as gases enter and leave. Layers of Atmosphere •Four layers based upon temperature changes occurring above the Earth. Ozone Layer The Troposphere •Extends to 18km above Earth. •Almost all weather occurs in this layer. •Densest layer. The Stratosphere •Extends from 18km-50km above Earth. •Ozone layer contained in the stratosphere. The Mesosphere •Has the same name as one of the layers of Earth…Meso means middle. •Extends to 80km. •Coldest layer…Temperatures as low as -93ºC The Thermosphere • The location of the Northern and Southern Lights (aurora’s). • Temps reach 2000ºC, but would not feel hot to us because the air is so thin there are few collisions of air particles. (diff. between temp and heat!) Energy in the Atmosphere •Reaches us through three mechanisms: – Radiation=transfer of energy through space. – Conduction=transfer of energy for warmer object to cooler object when brought into direct contact. – Convection=transfer of energy through currents. The Greenhouse Effect •Green house gases trap heat near Earth’s surface just the way windows of a car trap heat in the car. •Without the Greenhouse effect, Earth would be too cold for life. Greenhouse Gases •Water vapor, carbon dioxide, methane, nitrous oxide, Ozone. Section 3- Hydro and Biosphere The water cycle: Continuous movement of water. – Evaporation: water heated below the boiling point to become vapor which rises into the atmosphere. – Condensation: vapor forms droplets on dust that then become clouds. The droplets begin to collide, form larger droplets that can no longer be suspended…rain. – Precipitation: Water in the form of rain, snow, sleet or hail. Other parts of the Hydrologic cycle: • Percolation/infiltration: Precipitation soaks down into the soil layers. • Run-off: Water runs along the surface of the land and is carried to waterways. • Transpiration: Evaporation via Flora (plants, trees, grasses). • Collection: Water gathering in an area (such as a lake or into the water table or aquifer). The World Ocean •Although the oceans all have individual names, Atlantic, Pacific, Indian, etc., they are all actually a large, single, interconnected, body of water. – Largest=Pacific, next =Atlantic, smallest=Arctic. The World Ocean Hydrothermal Vents •Openings in the ocean floor where hot, mineral-rich water streams into the ocean. •Usually occurs where tectonic plates are separating and form deep fractures. Hydrothermal Vents The Oceans •Three parts: – Surface zone: warmest, upper- most, 0-350m deep. – Thermocline: Temperature drops quickest. Middle layer. 350- 700m. – Deep Zone: 750m-bottom. Temps near freezing (2ºC). Functions of the Oceans •Absorb and store energy from the sun light. – Regulates Earth’s temperatures. – Causes land areas near warm currents to have more moderate temperatures (ex: temp of Aruba is generally near 80ºF) Fresh Water • 3% of the Earth’s water. • Mostly tied up in icecaps and glaciers. – Antarctic ice cap is as large as the U.S. and is 3km thick. • Other fresh water found in lakes, rivers, wetlands, soil and rock layers. The Biosphere-Life on Earth •Earth to biosphere ratios are comparable to an apple and its skin. – The biosphere is a very thin layer. •Factors to life on Earth: – Temperatures between 10-40ºC. – Liquid water. – Energy source. Energy Flow •Closed system: Energy is free to flow in and out but matter is not. – Dead organism becomes nutrient factor for the living. •Open system: Matter and energy are exchanged between the system and surrounding environment.
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