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Investigation of Earth's interior and atmosphere.
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The Earth as a Planet
Earth as a Planet
• Densest planet in the solar system
• Largest terrestrial planet • Only planet (currently) to have
– Plate tectonics – Liquid water on the surface ? – Life ? – Oxygen-rich atmosphere
PTYS/ASTR 206 Earth 3/4/08
PTYS/ASTR 206 Earth 3/4/08
The Earth’s Internal Structure
• The Earth’s inner and outer cores are composed of almost pure iron with some nickel mixed in
• The mantle is composed of iron-rich minerals
• Both temperature and pressure steadily increase with depth inside the Earth
Earthquake Distribution
PTYS/ASTR 206 Earth 3/4/08
Drift of Continental Plates over time• About a few centimeters per
year – Ranging from about the rate at
which fingernails grow, to that of hair growth !
• The continents were all together around 250 million years ago – The Earth is 4.56 Billion
years old – That is only 0.4% of the
lifetime of the Earth • In terms of a human
lifespan, that’s about 4 months !
Plate tectonics is responsible for most of the major features of the Earth’s surface, including mountain ranges, volcanoes, and the shapes of the continents and oceans
• Plate tectonics is involved in the formation of the three major categories of rocks: !
• igneous rocks – cooled from molten
material • sedimentary rocks
– formed by the action of wind, water, and ice
• metamorphic rocks – altered in the solid
state by extreme heat and pressure
PTYS/ASTR 206
• Earth’s atmosphere consists of mostly nitrogen (78%) and oxygen (21%). !
• It is divided into layers – Other planets have a similar
structure, although the details are different
!• In the troposphere,
temperature decreases with altitude !
• Ozone molecules in the stratosphere absorb ultraviolet light; thus temperature rises with altitude
The Structure of Earth’s Atmosphere
Evolution of Earth’s Atmosphere
• First Atmosphere – Mostly H2 and He !
• Second Atmosphere – Greenhouse gases:
• H2O, CO2, SO2
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The Importance of Earth’s Atmosphere on the Surface Temperature
• Heat input from Sun vs. Heat radiated by Earth. !
• This gives a temperature that is much smaller than the actual one – The Earth should be well below
freezing !
• Why is the Earth so warm? – The Greenhouse effect !
PTYS/ASTR 206 Earth 3/4/08
PTYS/ASTR 206
Earth 3/4/08
Greenhouse gases
• Molecules that absorb infrared radiation !
• Natural – Water Vapor H2O (most abundant) – Carbon Dioxide, CO2
– Methane, CH4
– Nitrous oxide, NO2 !
• Increased during industrial revolution – Carbon dioxide (CO2) – Methane (CH4) – Nitrous oxide (NO2) – Chlorofluorocarbons
Greenhouse effect -- results
• Earth is warmed up – With no Greenhouse Effect, average temperature would be below
freezing !
• Changing amount of Greenhouse Effect changes Earth’s temperature, weather – Changes not uncommon during Earth history – Usually changes what species are present – Details almost impossible to predict
As these trees grow where do they get the bulk of their mass from?
Carbon Cycle• Carbon cycles through atmosphere, oceans,
rocks, living matter. • 1 gallon of gasoline = 100 tons of plant life • 1 year of fuel consumption = ~500 years of plant
life
Climate Records– Sediment cores – Ice cores
• Temperature • Abundance of greenhouse gasses
Ice Cores
Effects of Melting Ice• Loss of sea ice
– Animal habitat (polar bear) – Northwest passage
• Melting grounded ice results in changes in sea level – Greenland Ice Sheet – Antarctic Ice Sheets
Atmospheric Circulation• Air flows from High pressure to Low pressure
– High pressure – moist warm air (equator) – Low pressure – cool dry air (poles) !
• Because the Earth spins we experience a Coriolis Effect. – This force is responsible for altering the path
of an object moving on a rotating object !!
!!!!!
Air currents without rotation ^
<- Air currents with rotation
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