Transcript The Dynamic Earth

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, uppermost, 0-350m deep.
– Thermocline: Temperature drops
quickest. Middle layer. 350700m.
– 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.