Transcript Miller Chapter 6.1-6.2 PPT (Part 1)

APES Bell Ringer
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Miller Chapter 6.1-6.2
Atmosphere and Weather
AP Environmental Science
www.ai.mit.edu/people/jimmylin/pictures/2001-12-seattle.htm
Origin of Modern Atmosphere
• Original atmosphere: Hydrogen and Helium
• 2nd atmosphere evolved from gases from molten
Earth
– H2O, CO2, SO2, CO, S2, Cl2, N2, H2, NH3, and CH4
– Allowed formation of oceans and earliest life
• Modern Atmosphere
– evolved after Cyanobacteria started photosynthesizing
– oxygen produced did not reach modern levels until about
400 million years ago
www.degginger.com/digitalpage.html
Continental Drift
• ~230 million years ago
– 1 giant landmass on Earth =
Pangaea
• As the continents moved
toward their present-day
locations the
– Sea level dropped
– Volcanoes erupted
– Earth’s surface was pushed
upward.
• Effects on weather:
– Drop in temperature and
precipitation all over the
Earth. These changes were
gradual.
Extinction of the Dinosaurs?
• Climate change = Extinction of the dinosaur?
• Plants extinct Dinosaurs that ate these plants
became extinct  Meat-eating dinosaurs that
depended on plant-eating dinosaurs died
• Other scientists believe that dinosaurs became
extinct as the result of a giant asteroid striking
the Earth 65 million years ago (many theories!)
Earth’s Atmosphere
• Compared to the size of the
Earth (104 km), the atmosphere
is a thin shell (120 km).
• If the Earth was an orange, the
atmosphere would be the
pesticides on its peel
http://www.gsfc.nasa.gov/gsfc/earth/pinatuboimages.htm
Atmosphere
Layers
•
•
•
•
•
•
Exosphere
Thermosphere
(Ionosphere)
Mesosphere
Stratosphere
Troposphere
(closest to Earth)
Troposphere
•
•
•
•
8 to 14.5 kilometers high (5 to 9 miles)
Most dense
Temperature decreases as altitude increases
Weather is found here!
Stratosphere
• Extends to 50 kilometers (31 miles) high
• Dry and less dense
• Temperatures increase as altitude increases
– Due to the absorption of ultraviolet radiation
• Ozone layer absorbs and scatters the solar
ultraviolet radiation
• 99% of "air" is located in first two layers
The Atmosphere
• Mesosphere
– very little
atmosphere
– coldest layer
• Thermosphere
– ionosphere
– aurora borealis
– hottest layer
• 1000 C
120
Atmospheric pressure (millibars)
0
200 400 600 800 1,000
75
Temperature
110
Pressure
65
Thermosphere
100
55
Mesopause
80
45
70
60
Stratopause
35
50
Heating via ozone
40
30
25
Altitude (miles)
Altitude (kilometers)
90
Mesosphere
Stratosphere
Tropopause
Ozone “layer”
20
15
Heating from the earth
10
0
(Sea
Level)
5
–80
–40
0
40
80
Temperature (˚C)
120
Troposphere
Pressure = 1,000
millibars at
ground level
Atmosphere
Composition
•
•
•
•
Nitrogen (N2, 78%)
Oxygen (O2, 21%)
Argon (Ar, 1%)
Variety of other very
influential components are also
present which include the Water (H2O, 0 7%), "greenhouse" gases or Ozone (O3, 0 0.01%), Carbon Dioxide (CO2, 0.01-0.1%),
What gas was
originally
Review
Questionsnot in the
atmosphere?
A. Carbon dioxide
B. Water
C. Oxygen
D. Methane
The gas that
composes
78% of the
Review
Questions
gases in the atmosphere is:
A. Oxygen
B. Nitrogen
C. Carbon Dioxide
D. Ozone
The atmosphere
layer
in which most
Review
Questions
of the weather occurs is the:
A. Troposphere
B. Stratosphere
C. Mesosphere
D. Thermosphere
E. Exosphere
Weather: A Brief Introduction
 Weather
 result of the atmospheric conditions in a particular
area over short periods of time, typically over hours
or days
 EX:
temperature, pressure, moisture content, precipitation,
sunshine, cloud cover, and wind direction
CLIMATE
Average pattern of
weather for a particular
region
LONG TERM
OBJ 6.2
• 2 Main factors
– Temperature
– Precipitation
• Amount
• Distribution
Factors that affect
temperature:
– Latitude
– Elevation
– Closeness to large
bodies of water
Climate
Closeness to Large Bodies of Water
Water
moderates the
temperature
creating cooler
summers and
warmer
winters
Elevation
Short Term Changes in Climate
• Changes in ocean currents and global winds.
• Ocean currents help transfer heat to the
atmospheregenerates global windshelp
move ocean currents.
• Any major change in an ocean current can
cause a change in climate
– El Nino!!! (We will discuss this at the end! )