Atmosphere 1: Structure

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ATMOSPHERE 1
ppt. by Robin D. Seamon

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COMPOSITION &
STRUCTURE OF THE
ATMOSPHERE
VOCABULARY:
atmosphere air pressure
ozone troposphere
smog stratosphere
primary pollutant mesosphere
secondary pollutant thermosphere
acid rain
mist
fog
haze

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Atmosphere- gas layer of Earth
• Composition has changed dramatically over
Earth’s history

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• Nitrogen — 78 %
• Oxygen — 21 %
• Argon — 0.93 %
• Carbon dioxide — 0.04 %
• Trace amounts of neon,
helium, methane,
krypton and hydrogen
VARIABLE COMPONENTS:
• water vapor
• Pollutants
• Ozone
• Microscopic particles
TODAY

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Oxygen: (21%)
• Oxygen breathed in by many organisms on the planet
and out by plants
• Does NOT affect the weather
Carbon Dioxide: (0.04%)
• Absorbs heat
• Influences the temperature
of the planet
• Breathed in by plants &
some protists
ATMOSPHERIEC INFLUENCERS

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Water Vapor:
• Source of clouds & precipitation
• Varies over different parts of the globe
• Absorbs heat
Water vapor varies with location

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Ozone
• Form of oxygen containing 3 atoms of O
in each molecule
• Concentrated in low level of the stratosphere
• Absorbs harmful UV rays from the sun
• Smog: When ozone forms lower in the troposphere,
over cities, for instance, it can cause asphyxiation
(smothering) to life

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Microscopic particles:
Atmospheric movements can suspend small particles in
the air and be moved by the wind:
• Pollutants
• Fine soil particles
• Microorganisms
• Sea salts
• Smoke/soot from fires
• pollen

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POLLUTION:
• Particle Pollution (particulate matter)
• Ground-level ozone
• Carbon monoxide
• Sulfur oxides
• Nitrogen oxides
• Lead

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• mobile sources-- such as cars, buses, planes,
trucks, and trains
• stationary sources – such as power plants, oil
refineries, industrial facilities, and factories
• area sources – such as agricultural areas, cities,
and wood burning fireplaces
• natural sources – such as wind-blown dust,
wildfires, and volcanoes
SOURCES

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Primary Pollutants: are emitted directly from a source

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Secondary Pollutants: form in the atmosphere when
reactions occur among primary pollutants & other
substances
• Sulfur dioxide combines with oxygen to make sulfur
trioxide, which combines with water to make acid rain

13. • Nitrogen oxide absorbs solar radiation, beginning a
chain of reactions which use organic compounds in
the atmosphere to produce photochemical smog
(brown haze)
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Secondary Pollutants: form in the atmosphere when
reactions occur among primary pollutants & other
substances

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Pollutants

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Wind can move Pollutants

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mist & fog
• water droplets in
the air
• only difference is how
far you can see
haze
• reflection of sunlight
off air pollution
smog
pollution causes this
low-lying ozone

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STRUCTURE OF ATMOSPHERE
• Atmosphere thins as you move away from Earth until
there are no molecules… OUTER SPACE

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Air pressure: weight of air above, pressing down with gravity
• Changes with
elevation
50% of air
lies below
this altitude:

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STRUCTURE

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TEMPERATURE IN THE
ATMOSPHERE
VOCABULARY:
air temperature windward coast
elevation leeward coast
altitude albedo
solar radiation isotherms
conduction ocean currents
convection
radiation
absorption
transmission
reflection
scattering

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Air Temperature- changes with elevation
• Changes at
different
elevations
Mt. Ranier, WA

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Air Temperature- changes as you move away from the earth
• Each layer has its own pattern of temperature change.
Temperature DECREASES
with altitude
Temperature INCREASES
with altitude
Temperature INCREASES
with altitude
Temperature DECREASES
with altitude

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SOLAR ENERGY
Solar energy excites/warms the particles in the
atmosphere, causing wind and weather
1. Conduction- transfer of heat from one molecule to
another (warmer to cooler object)
• air is a POOR conductor of heat, affecting only the air
just above the
surface of land/
water

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SOLAR ENERGY
2. Convection- transfer of heat by mass movement/
circulation within a substance; (most atmospheric
heat is transferred this way)
• Wind: warm air is
less dense and rises;
cooler, denser air
drops to take its
place

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SOLAR ENERGY
3. Radiation- transfer of energy through electromagnetic
waves from the sun
THREE RESULTS:
• Absorption: energy is absorbed by the object (50%)
• Transmission: water & air do not gain or contribute to
the energy, just lets it pass
• Reflection: bouncing off the
object (30%)

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SOLAR ENERGY
Absorption: energy is absorbed by the object (50%)
• Greenhouse effect - Energy is reradiated skyward & is
absorbed by certain atmospheric gases; keeps Earth
warm & habitable
Water vapor (H. 2O)
Carbon dioxide (CO. ...
Methane (CH. ...
Nitrous oxide (N. 2O)
Ozone (O. ...
Chlorofluorocarbons (CFCs)
Hydrofluorocarbons (incl.
HCFCs and HFCs)

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SOLAR ENERGY
Transmission: water & air do not gain or contribute to the
energy, just lets it pass

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SOLAR ENERGY
Reflection:
• reflection: bouncing back at the same intensity
(30%)
• scattering: bouncing back by spreading the rays;
weaker intensity

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Air Temperature- changes with latitude
• Cooler, the
farther from
the equator

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Air Temperature- other factors
Surfaces heat the air above it:
Differences in heating of surfaces
• Land heats faster & to a higher temp than water
• Land cools faster & to a lower temp than water

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Ocean Currents
• Oceans move warm water from the equator towards
the poles, affecting the air above it
Earth’s tilt & position in revolution: seasons

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Air Temperature- other factors
Geography
• Windward coast
Coastal areas with
prevailing winds from the
ocean to shore: milder
temps
• Leeward coast
Coastal areas with
prevailing winds from the
land to the ocean:
Erueka, Ca
NYC

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Air Temperature- other factors
Geography
• Landform barriers:
Mountains acting as
barriers
Maritime climate:
Continental climate:
Seattle, WA
Spokane, WA

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Cloud cover & albedo
• Albedo: reflection of light back into the atmosphere
by snow/ice & clouds
• Shade is cooler during the day
• Cloud cover keeps the surface warm at night

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Isotherms
• Lines that connect points that have the same temperature

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WATER IN THE ATMOSPHERE
VOCABULARY:
solid dew
liquid hydrometer
gas psychrometer
evaporation dry bulb
condensation wet bulb
precipitation air compression
sublimation air expansion
deposition adiabatic temperature
frost stable air
humidity unstable air
saturation
relative humidity
dew point

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W A T E R S T A T E S :
Solid- ice Liquid- water Gas- water vapor

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Water Cycle

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C H A N G E S O F S T A T E :
LIQUID TO GAS: evaporation
energy moves from the wet surface to the air, causing
cooling
GAS TO LIQUID: condensation
Generates dew, clouds & fog as the vapor gives back the
energy it received in turning into a vapor earlier
SOLID TO GAS: sublimation
Solid to a gas without going through liquid phase
GAS TO SOLID: deposition
Gas to solid without liquid phase: frost

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FROST
(Deposition)

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Mt. Everest
(Sublimation)

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Humidity- amount of water vapor in the air
1. Saturation- Can hold no more…
warm air contains more water vapor than the
saturated cold air
2. Relative humidity- ratio of air’s actual water vapor
content compared with the amount of water vapor
the air can hold at that temperature and pressure

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Dew point- temperature to which a parcel of air needs
to be cooled to reach saturation
• Cool the air past the dew point: makes dew, fog,
clouds
• Dew- water droplets formed on surfaces due to the
cooling of these objects to below the temperature of
the air near them… water condenses on the objects

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MEASURING HUMIDITY
Hygrometer- measures humidity
• Psychromoter
• Two thermometers:
• Dry bulb- gives present air temperature
• Wet bulb- has a cloth wick at the end
• 1. Wick is wet
• 2. Swing the thermometer
• 3. As water evaporates from the which, heat is
absorbed by the evaporating water, causes the
temperature in the wet bulb to drop (wet bulb
temperature)
*** Drier air evaporates more water
*** Saturated air will not evaporate anything

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*** The larger the difference between temperatures,
the lower the relative humidity

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Adiabatic Temperature Changes- temperature changes
that occur without heat being added or subtracted
• Air Compression:
air becoming pressed
together- becomes
warmer due to the force
applied to it
• Air expansion:
air allowing to spread out/
push on air around it-
becomes cooler equal to
the amount of energy used

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CLOUDS: air moves upward, cools to its dew point:
condenses, forms clouds

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AIR MOVEMENT
VOCABULARY:
stable air
unstable air
orographic lifting
rain shadow effect
frontal wedging
convergence
convective lifting
thermals

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Stable air- air that tends to remain in its original position
(resists vertical movement)
Unstable air- air that tends to rise vertically
HOW DOES AIR MOVE?
1. orographic lifting
2. frontal wedging
3. convergence
4. localized convective lifting

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Orgraphic lifting
1. elevated terrains (mountains) block air flows
2. air gets pushed up the mountain, condenses & rains
(windward side) before passing over the mountain
• Rainy Seattle, US
3. rain shadow effect- the air mass moves to the other
side of the
mountain
(leeward side),
now dry; many
deserts are on
the leeward
side of
mountains

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Great Basin Desert, US

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frontal wedging- air masses of different temperature
collide producing a front
1. warm air mass collides with cold air mass
2. cooler air mass is a barrier so warm air rises over it
3. produces middle-latitude cyclones

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convergence - air masses flowing from different
directions collide and flow upwards
• Florida peninsula

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convective lifting- when a surface becomes noticeably
warmer than other surfaces, causing the air to warm &
move upwards in thermals
• over a paved parking lot
• birds use thermals to gain height
• when warm parcels rise above condensation
level, clouds may produce mid-afternoon rain
showers

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WHEN
Stable air forced up:
widespread clouds, little
vertical thickness;
precipitation is
light/moderate
dreary, overcast day
WHEN
Unstable air forced up:
towering clouds, build
thunderheads; make
thunderstorms or tornado
fast stormy weather

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Stable air forced up

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unsable air forced up

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CLOUD FORMATION
VOCABULARY:
dew rain
clouds snow
cirrus sleet
cumulus glaze/freezing rain
stratus hail
high clouds collision-coalescence process
middle clouds
low clouds
fog
cloud droplets
precipitation
Bergon process
supercooling

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CLOUD FORMATION
Saturated air cools to its dew point and condenses onto
an object
• dew: grass, car, objects on surface
• clouds: tiny microscopic particles in the air
(condensation nuclei)

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CLOUD TYPES
Form
Cirrus:
high, white, thin
wispy
Cumulus:
rounded cloud
masses with flat
base
Stratus:
sheets/layers
covering the sky

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CLOUD TYPES
Height
High:
icy crystals
6,000m high
----------------
cirrus
cirrostratus
cirrocumulus
Middle:
2,000-6,000 m
“alto” in name
-----------------
altocumulus
altostratus
Low:
below 2000 m
-----------------
stratus
stratocumulus
nimbostratus

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Fog- cloud with its base at or near the ground
1. formed by cooling: thin layer
of surface is cooled below is
dew point
2. formed by evaporation:
when cool air moves over
warm water, enough vapor
saturates the air to make
fog

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PRECIPITATION
Cloud Droplets: SIZE 20 micrometers
Precipitation: SIZE need to be 1 million times larger to
reach surface without evaporation

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Cold Cloud Precipitation
Bergeron process:
• supercooling- phenomenon of cloud droplets of not
freezing until well below zero: -40 degrees F
• water will freeze
when in contact with
particulate matter
• When heavy enough
gravity pulls them to
earth

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Warm Cloud Precipitation
collision-coalescence process
• water droplets in the
air collide, bounce, or
combine to form a
larger droplet

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TYPES OF PRECIPITATION
depends on temperature of the lowest parts of the
atmosphere
rain- drops of water from a cloud
snow- low temperatures with low moisture content;
six-sided crystals form
• temperatures warmer than 23 degrees F form
larger clumps with higher moisture contents

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sleet- fall of small particles of clear ice; layer of air with
temps above freezing must overlie a subfreezing layer
below
glaze/ freezing rain- raindrops freeze as they fall; turn to
ice when they hit objects

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hail- forms in cumulonimbus clouds- small ice pellets get
blown upwards into the atmosphere, get coated with
more ice over and over again until the pull of gravity pulls
it down.