Transcript Earth Systems

Earth Systems
Things to think about
•
Look at the world map
1. Earth’s surface is not smooth. What do you
think causes variations in its surface?
2. Is the Earth changing? List any evidence
(features or processes) that it is or is not
changing.
3. What changes might occur to Earth’s
surface
1. On a time scale of 100 years
2. On a long time scale (10,000 – 1,000,000s)
USGS recent earthquakes
• Recent Earthquakes
• http://earthquake.usgs.gov/earthquakes/
– The above link is to recent earthquakes
• What does the pattern of earthquakes and
volcanoes suggest?
• How about the shape of the continents?
Tectonic plates
Animation: breakup of pangea
• http://www.classzone.com/books/earth_sci
ence/terc/content/visualizations/es0806/es
0806page01.cfm?chapter_no=visualizatio
n
Structure of the Earth
Heat: where did it (does it) come from?
How do scientists know
about the Earth’s structure?
• One way: earthquake waves that pass
through the Earth and over the Earth’s
surface
– P waves (compressional, primary)
– S waves (shear, secondary)
• Model
Plate boundaries
More evidence of
continental drift
• The colored bands
represent where
fossils of different
critters and plants
have been found.
• They span two or
more continents.
• These creatures do
NOT swim—or they
are freshwater
animals—so the
continents must
have been
connected
Convection in the mantle
• http://www.classzone.com/books/earth_sci
ence/terc/content/visualizations/es0805/es
0805page01.cfm?chapter_no=visualizatio
n
• Show the mantle model
Sea-floor spreading
• Mid-ocean ridge
• Diverging plate boundary
• How do we know?
1. Prediction about age of sea floor
2. Magnetic reversals
3. It’s still spreading!
What does it mean…
• To refer to the Earth as a system?
• Think ``machine’’ versus ``parts’’
Parts of the earth system
•
•
•
•
Lithosphere (geosphere)
Hydrosphere
Atmosphere
Biosphere
Open vs closed system
• Open: exchanges energy, matter, and/or
information with other systems
• Closed: isolated and self-contained
• Is the Earth open or closed?
– Energy?
– Matter?
Hydrosphere
•
What happens to water
• With one partner, sketch out where you
think water goes.
• Start with water in the ocean.
Water cycle
• Nasa's water cycle movie
Ocean water
• 96.5 % H2O by mass
• Remainder: various salts [35 parts per thousand]
• Temperature:
– Warmer near the surface
– Deep water (below ~1000 m) is equally cold
• Density:
– Colder, saltier water is denser = deep water
Salinity patterns
number is “parts per thousand”
•
Ocean currents
• Water flows horizontally
• Causes?
– Surface: wind
– Deep: density differences – salinity,
temperature
• Ocean conveyor - YouTube
Vertical movements
• Upwelling
– Deep, cold water rises to replace surface
waters that flow away
– Brings nutrients to surface
– Site of rich fisheries
Freshwater
• Review: Where is the freshwater on
Earth, and in approximately what
percentages?
– Ice caps, glaciers:
– Aquifers:
– Surface water:
– Atmosphere (and biosphere):
69 %
30 %
0.9%
0.1%
Aquifers
• Rock layers below the surface of the
earth that are porous and hold water.
• Water moves through an aquifer just as
water moves in a river.
• See All the Water in the world, Google
Earth
Aquifer
•
How water moves in aquifers
• In a word:
– SLOWLY!
• Depends on the size of the pore spaces.
– Smaller spaces mean slower flow
• At the other extreme: Large ``pore’’ space
of a cave might have a river run through it
Aquifers
• Supply drinking water
• Anyone who has a well gets water from an
aquifer
• About HALF of all Americans get most of
their water from wells
• RECHARGE is key—the infiltration of
water back to the aquifer
Aquifers
• Is the water clean?
• Water moving through pore spaces of rock
or gravel is naturally filtered
– ``coffee filter’’ keeps coffee grounds behind
• Dissolved chemicals can contaminate an
aquifer and water pumped from its wells.
– The filter doesn’t prevent the ``coffee’’ from
going through
•
What is this picture?
•
• >97% of the water flowing into Lake Mead
comes from snow melt and rain—runoff—
in the Rocky Mts, the source of the
Colorado R.
Lake Mead
Lake Mead water levels
• http://www.arachnoid.com/NaturalResourc
es/
US drought monitor
• http://www.drought.unl.edu/dm/monitor.ht
ml
The atmosphere
Where did the atmosphere come
from?
• May have developed
from gases released by
volcanoes.
• This is Kilauea in
Hawaii.
• Early atmosphere very
different from today.
• NO O2, but H2O, CO2,
CH4, HCl
Composition
• Nitrogen – 78 %
• Oxygen – 21 %
• All the rest???
– Carbon dioxide,
methane, CFCs,
• Water vapor is
variable, from 0 to
4%
Structure
• 4 major layers
• Troposphere: where the
weather is
• Tropopause: jet stream
• Stratosphere: ozone
layer
• 99% of the total mass of
the atmosphere is below
32 km
• Temp. drops 5-10 C
every 1 km in
troposphere
Impact of air density
• Where is air densest? Where is it least
dense?
• How does this affect a batted baseball?
• http://profhorn.meteor.wisc.edu/wxwise/ba
seball/homerun.html
NOT true any
longer: air
conditioners and
refrigerators no
longer contain
CFCs
BUT: CFCs last
a long time in
the atmosphere
(decades) so
these gases are
still doing
damage.
Troposphere
• Our sphere
• Weather
• Notice: patterns
– Temperature
– Winds
• Layer ends when
temp. no longer
varies with height =
tropopause
•
Water cycle
• Connects ocean
and atmosphere
• Key pt: what
happens in the
atmosphere
depends a lot
on what
happens in the
ocean
Solar energy
•
• Energy from sun
• Some absorbed by
gases (O3, H2O)
• Some reflected by
clouds and by the
Earth’s surface
• Last is called albedo
albedo
• Notice snow,
water, and
clouds
• What feedback
effects would
you expect
from melting of
ice caps?
•
Energy transfer
•
Energy transfer
• Simplified earth: slow rotation to east,
no interaction of oceans and land
• Sun warms equator, air rises, spreads
north and south
• Cold air at poles sinks and replaces
• Air deflected by rotation, to right in N
hemisphere, to left in S hemisphere
– Coriolis effect