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The Dynamic Earth

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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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posted:3/3/2013
language:English
pages:34