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UNIT 2: ATMOSPHERE
INTRODUCTION
•Earth’s atmosphere and oceans
shapes our climate and weather
•The atmosphere is complex, and in a
state of dynamic balance
•Today, humans are altering this
balance
THE STRUCTURE OF THE
ATMOSPHERE
•Nitrogen, oxygen, argon, & water
vapor make up most of the
atmosphere
•Trace amounts of other gases
•Composition and ratio of gases
remain relatively constant
THE STRUCTURE OF THE
ATMOSPHERE
•Earth’s atmosphere extends 560 km
above the surface
•4 layers, each with different properties
THE STRUCTURE OF THE
ATMOSPHERE
•Troposphere- lowest layer (8-16 km up)
•Most weather occurs here
•Warmed up from below when solar
radiation heats the surface of Earth
•Temp decreases 6.5 degrees C per
kilometer of altitude
THE STRUCTURE OF THE
ATMOSPHERE
•Tropopause- layer of cold air (-60 C),
causes water vapor to condense
•Stratosphere- from tropopause to 50
km up
THE STRUCTURE OF THE
ATMOSPHERE
•Stratosphere- temps increase with
altitude
•90% of the ozone is here
•Not much water vapor due to
tropopause
•Stratopause- temps peack at (-3 C)
THE STRUCTURE OF THE
ATMOSPHERE
•Mesosphere- temps fall as you go up
•Lowest temp is -93 C at 85 km up
•Thermosphere- temps increase higher
than 1700 C
THE STRUCTURE OF THE
ATMOSPHERE
•Atmospheric pressure is greatest at
sea level (14.7 lbs/in^2)
•Pressure decrease as you increase
your altitude (less air pressing down on
you)
GREENHOUSE EFFECT
•Earth’s temp has remained fairly
constant over time
•Earth radiates energy back to space
balancing energy that we receive
from the sun
GREENHOUSE EFFECT
•Solar radiation may be absorbed by
clouds, the atmosphere, or the
surface of Earth.
•The albedo of Earth reflects some of
the solar radiation back to space
GREENHOUSE EFFECT
•Some reflected energy from Earth is
trapped in the atmosphere
•Greenhouse Effect
•Clouds, water vapor, and greenhouse
gases can absorb this solar radiation
GREENHOUSE EFFECT
•The greenhouse gases (carbon
dioxide, methane, and nitrous oxide)
radiate the energy back to Earth and
warms the planet even more
MATH
•You have a container holding 150
parts of atmospheric gas.
•Calculate the following amounts of
gases in the container
MATH
•Nitrogen
•Oxygen
•Argon
•Carbon Dioxide
•Ozone
Helium
Methane
Nitrous Oxide
MAJOR GREENHOUSE GASES
•Greenhouse Gas= GHG
•Most occur naturally in the
atmosphere
•Some are synthetic
MAJOR GHGS
•Carbon Dioxide= CO2
•GHG affected directly by humans
•Combustion of fuels or decay of
biomass
•Natural sources= volcanoes,
breathing, fires
MAJOR GHGS
•Main sources of CO2 increase
•Burning fossil fuels
•Deforestation
• less plant life or different plant life
means the ecosystem cannot store as
much carbon
MAJOR GHGS
•Methane= CH4
•Anaerobic decay (without oxygen)
•Fermentation (farts) in ruminant
animals like cattle
•Manure/wastewater treatment
•Fossil fuel combustion
MAJOR GHGS
•Nitrous Oxide= N2O
•Fertilizer use
•Animal waste management
•Fossil fuel combustion
•Industrial activities
MAJOR GHGS
•Hydrofluorocarbons (HFCs) &
Perfluorocarbons (PFCs)
•Synthetic chemicals
•By-product of aluminum smelting
•Refrigeration, air conditioners
•Foam-blowing insulation
MAJOR GHGS
•The increase in GHGs increases the
ability of Earth’s atmosphere to trap
radiant energy
•It takes many years to notice the
temp. change
•Oceans can store lots of heat
VERTICAL MOTION IN THE
ATMOSPHERE
•Many weather patterns start with rising
air
•Increasing the temp of air with
constant pressure causes it to expand.
•Warmer air is less dense
•Less dense air is more buoyant than
denser air
VERTICAL MOTION IN THE
ATMOSPHERE
•Water is a key factor in
weather/climate
•1-2% of atmosphere is water
vapor
VERTICAL MOTION IN THE
ATMOSPHERE
•Relative humidity= compares amount
of water vapor present to the max
amount air can hold
•100% relative humidity=air cannot
hold any more water vapor
(muggy air)
VERTICAL MOTION IN THE
ATMOSPHERE
•As air warms, the amount of water
vapor air can hold increases.
•Water vapor concentrations are
highest in warm regions, and lowest
near the poles
VERTICAL MOTION IN THE
ATMOSPHERE
•Adding moisture to air makes it less
dense (wet air will rise)
•Latent energy= moist air has the
potential to warm the surrounding air
when the water condenses
VERTICAL MOTION IN THE
ATMOSPHERE
•Dew point= temperature at which air
would have to cool to be fully
saturated (can’t hold any more
water)
•When air cools to its dew point, clouds
form and precipitation can start
VERTICAL MOTION IN THE
ATMOSPHERE
•Unstable atmosphere is more likely to
produce clouds and storms
•Air masses rise and form clouds if they
have enough water vapor to warm
them as they expand
VERTICAL MOTION IN THE
ATMOSPHERE
•Air masses rise by:
•Winds pushing them up mountain
ranges, cooling the air and forming
clouds
•Convergence= air masses collide,
pushing one up (thunderstorms)
VERTICAL MOTION IN THE
ATMOSPHERE
•Convergence continued:
•Cold & warm front collide
• Cold=denser, so it sinks
• Warm air rises, cools, and clouds form
• If it is lifted fast/strong enough, you get
intense storms
ATMOSPHERIC CIRCULATION
PATTERNS
•Atmospheric circulation= movement
of air masses
•Vertical=Warm air rising=vertical
•horizontal-=Wind created by air
moving from high to low pressure
ATMOSPHERIC CIRCULATION
PATTERNS
•Isobars= parallel lines on a weather
map indicating areas of air with the
same pressure
ATMOSPHERIC CIRCULATION
PATTERNS
•Sea breezes (Day)
•The land heats up faster on land, air
rises
•Warm air moves over water and cools
•Air of water is cooler, moves in to land
ATMOSPHERIC CIRCULATION
PATTERNS
•Sea Breeze (Night)
•Land cools quicker than water, cool
air moves out to water
•Air over water warms, rises
•Warm air moves back over land and
cools
ATMOSPHERIC CIRCULATION
PATTERNS
•Wind over very long distances appear
to curve
•Coriolis Fore=caused by Earth’s
rotation
• Equator spins faster than near the
poles
ATMOSPHERIC CIRCULATION
PATTERNS
•Earth spinning causes objects on Earth
to have angular momentum
•Objects spin faster the closer they are
to the reference point
•Figure skater pulling in their arms
ATMOSPHERIC CIRCULATION
PATTERNS
•Same effect on air mass going from
equator to pole
•The closer to Earth’s reference point
(the poles) the faster the air mass spins
•Northern hemisphere (turn right)
•Southern hemisphere (turn left)
ATMOSPHERIC CIRCULATION
PATTERNS
•Coriolis force causes hurricanes in the
Northern Hemisphere to spin
counterclockwise and clockwise in
the Southern Hemisphere
ATMOSPHERIC CIRCULATION
PATTERNS
•Air circulates clockwise in a high
pressure system
•Air circulates counterclockwise in a
low pressure system
ATMOSPHERIC CIRCULATION
PATTERNS
•Air move towards and up in low
pressure systems
•Air move down and out of high
pressure systems
ATMOSPHERIC CIRCULATION
PATTERNS
•Hadley Circulation (starting at the
equator)
•Warm, moist air rises
•The warm air moves to cooler regions
north or south of the equator
ATMOSPHERIC CIRCULATION
PATTERNS
•As the air mass moves, it looses its
moisture through precipitation
•Cool, dry air descends
•The air then warms and collects
moisture up and along the surface
•Repeat
CLIMATE, WEATHER, AND STORMS
•Weather=atmospheric conditions at a
certain place and time
•Climate= long-term weather trends in
a specific region
•Climate is what you expect, weather
is what you get
CLIMATE, WEATHER, AND STORMS
•Circulation patterns create
predictable climate zones
•50-60 degrees north & south latitudes
have lots of precipitation
•30 degrees north and south latitudes
are dry from descending air
CLIMATE, WEATHER, AND STORMS
•Air pressures increase sharply
between middle latitudes (40
degrees) and the poles
•This causes the jet stream
CLIMATE, WEATHER, AND STORMS
•Jet stream flows west to east
•Transport heat as they shift north and
south
•Jet stream bring much of the weather
to our area
•In the winter, a dip in the jet stream
from Canada brings arctic air to us
CLIMATE, WEATHER, AND STORMS
•Hurricanes
•Form over tropical waters (8-20
degrees latitude)
•Most active area is western Pacific
CLIMATE, WEATHER, AND STORMS
•Signs of a potential hurricane
•Appearance of a tropical disturbance
•Feedback loop: falling pressure pulls
more air in, making more warm air rise,
releasing more pressure.
•Counterclockwise circulation
CLIMATE, WEATHER, AND STORMS
•Pressure near the top of the storm rises
•Air flows outward at the top, cools,
and then drops down forming
powerful winds
•This circulation keeps the storm strong
CLIMATE, WEATHER, AND STORMS
•If hurricanes move over cooler water
or land, they will diminish in size and
strength
GLOBAL CARBON CYCLE
•GHG emissions are affecting the
natural carbon cycling between land,
atmosphere, and oceans
•The rate land and ocean takes in
carbon determines how much is left
over in the atmosphere
GLOBAL CARBON CYCLE
•Humans are interfering with the
natural balance of the carbon cycle
•Atmospheric CO2 is rising rapidly and
higher than it has been in 650,000
years.
GLOBAL CARBON CYCLE
•In recent decades, only half the CO2
added by humans stayed in the
atmosphere
•The oceans and land stored the rest
GLOBAL CARBON CYCLE
•On average, carbon spends this much time
in :
•Atmosphere=5 years
•Land plants=10 years
•Oceans=380 years
•Ocean sediments/fossil fuels=millions of
years
GLOBAL CARBON CYCLE
•Oceans can take in CO2, almost all in
the atmosphere, but it would take 500
years
•Only a small portion of the ocean
contacts the atmosphere
GLOBAL CARBON CYCLE
•Photosynthesis from marine and land
plants can take up CO2
•Most returns to the atmosphere later,
but some is stored for a long time