Thursday 10/4 Agenda 1. Read ORANGE lab on your table 2. Review Notes Air, Weather, Climate slides 1-15 3. Labs: Albedo

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Thursday 10/4 Agenda1. Read ORANGE lab on your
table2. Review Notes Air, Weather, Climate
slides 1-153. Labs Albedo Greenhouse
EffectHW finish questions chapter 23, Action
Savings in CO2, simulation on CO2
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AIR, CLIMATE, AND WEATHER

• CHAPTER 23
• APES

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Weather vs. Climate

• Weather
• Daily changes in the physical conditions of the
  atmosphere (moisture, temp, pressure, wind)
• Controlled by solar energy which controls winds
  which push moisture temp around planet

• Climate
• Long term patterns of weather in a particular
  area.
• Undergo cyclic changes over decades, centuries,
  and millenia

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Past Composition of the Atmosphere

• Millions of years ago mostly H and He
• Volcanic emissions added C, N2, O2 S
• Most oxygen was produced by photosynthetic
  bacteria and algae
• Now- 78 N2, 21 O2, 1 various gases (see chart)

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Earths Atmosphere

• compared to the size of the Earth (104 km), the
  atmosphere is a thin shell (120 km).

http//www.gsfc.nasa.gov/gsfc/earth/pinatuboimages
.htm
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AtmosphereLayers

• Thermosphere
• (Ionosphere)
• Mesosphere
• Stratosphere
• Troposphere

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Troposphere

• 8 to 14.5 km high (5 to 9 miles)
• most dense
• the temperature drops from about 17 to -52ºC
• almost all weather is in this region

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Stratosphere

• extends to 50 km (31 miles) high
• dry and less dense
• temperature in this region increases gradually to
  -3ºC, 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

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Thermosphere
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Mesosphere, Ionosphere, Thermosphere

• Mesosphere- middle layer
• -80ºC
• Thermosphere
• Ionosphere is lowest part of thermosphere where
  aurora borealis appears
• 1000 miles from surface
• 500 C-200 C

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Mesosphere, Ionosphere, Thermosphere

• Mesosphere- middle layer
• -80ºC
• Thermosphere
• Ionosphere is lowest part of thermosphere where
  aurora borealis appears
• 1000 miles from surface
• 500 C-200 C

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WEATHERPhysical conditions of temp, humidity,
pressure, wind, precip.
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The Great Weather Machine

• THE SUN causes global cycling of wind and water
  that creates our climate and distributes energy
  material thru environment.

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1. Seasonal Changes

• Occur because the earths axis is tilted
• Creates opposite seasons in the northern and
  southern hemisphere
• Factor that determines global air circulation
  patterns

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What types of radiation does the earth get?

• Visible light- comes thru undiminished
• Ultraviolet light- trapped by ozone layer in
  stratosphere
• Infrared radiation absorbed by CO2 and H2O in
  troposphere

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2. SOLAR RADIATION

• Incoming energy
• Insolation- absorbed sunlight
• Albedo- reflected sunlight
• Earths insolation albedo
• Surface oceans absorb 50 reflect 4
• Clouds absorb 3 reflect 20
• Atmosphere absorbs 16 reflects 6
• Bottom line
• 70 absorbed
• 30 reflected

http//www.epa.gov/hiri/about/videos.html Videos
on Heat Island Effect
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Quickwrite

• 1. How does the heat island effect form?
• 2. Which surfaces have high albedo? Why?

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3. THERMAL RADIATION

• Outgoing energy
• Mostly infrared radiation
• Can be reradiated from surface, clouds
  atmosphere
• Longer wavelengths absorbed by GASES in lower
  levels of atmosphere, trapping heat close to
  earths surface
• This phenomena is called the greenhouse effect
• Our planet would be too cold to live on if we
  didnt have the greenhouse effect.

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4. Ocean Currents

• Sea-surface temperature influences air
  temperature as the ocean exchanges heat with the
  overlying atmosphere.
• It also influences evaporation rates which are
  generally higher where sea-surface temperature is
  higher

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5. Convection Currents

• Sun heats earths surface
• Some heat transferred to air layers
• Air expands becomes less dense
• This lighter air rises is replaced by cooler,
  heavier air resulting in vertical convection
  currents
• http//www.school-portal.co.uk/GroupDownloadFile.a
  sp?File39949

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Convection Currents

• At the Equator- solar energy is intense- comes
  straight down so energy is high- creates energy
  surplus
• At the Poles- solar energy comes in at an angle
  so much energy lost from absorption thru long
  columns of air. Also, tilt of earths axis means
  no sunlight during much of winter
• This energy imbalance is evened out by mvmt of
  air water vapor in atmosphere by liquid water
  in rivers oceans.

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http//www.usatoday.com/weather/tg/wglobale/wgloba
le.htm
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6. Coriolis Effect

• Coriolis effect- Effect of earths rotation on
  wind direction
• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es1904/es1904page01.cfm

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Coriolis Effect

• Since winds are just molecules of air, they are
  also subject to Coriolis forces.
• Winds are basically driven by Solar heating.
• Solar heating on the Earth has the effect of
  producing 3 major convection zones in each
  hemisphere.
• If solar heating were the only thing influencing
  the weather, we would then expect the prevailing
  winds along the Earth's surface to either be from
  the North or the South, depending on the
  latitude.
• However, the Coriolis force deflects these wind
  flows to the right in the Northern hemisphere and
  to the left in the Southern hemisphere.

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7. Jet Streams

• Two major ones in N. Hemisphere
• Midlatitude- just below the circumpolar vortex
• Subtropical- about 30º N latitude
• Like a massive river of air moving wind, water,
  heat, etc.
• Usually westerly- come from the west

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8. Air Pressure

• caused by the weight of the air pressing down on
  the Earth, the ocean and on the air below
• falls as you go higher
• changes with weather
• air in a high pressure area compresses and warms
  as it descends
• the warming inhibits the formation of clouds,
  meaning the sky is normally sunny in
  high-pressure areas
• haze and fog might form
• the opposite occurs in an area of low pressure

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9. Humidity

• relative humidity is the amount of water vapor in
  the air compared with the potential amount at the
  air's current temperature
• expressed as a percentage
• depends on air temperature, air pressure, and
  water availability

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10. Cloud cover

• moisture in the atmosphere forms clouds which
  cover an average of 40 of the Earth at any given
  time
• a cloudless Earth would absorb nearly 20 percent
  more heat from the sun
• clouds cool the planet by reflecting sunlight
  back into space. (RememberThis is known as
  Albedo)
• However
• clouds reduce the amount of heat that radiates
  into space by absorbing the heat radiating from
  the surface and reradiating some of it back down
• the process traps heat like a blanket

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11. Precipitation

• Air containing water vapor cools in atmosphere
  and therefore condenses to form droplets of
  liquid water
• Rain liquid, falls, d gt0.5 mm (sphere)
• Freezing Rain occurs when drop touches frozen
  surface
• Sleet ice pellets, d lt 0.5 mm, begins as rain
  but enters air below freezing
• Snow water deposits in hexagonal nuclei below
  freezing
• Hail 5-190 mm in diameter, concentric rings of
  ice

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12. Fronts

• Boundary btwn 2 air masses of different temp.
  density
• Cold-
• Cooler air displaces warmer air
• Cold air more dense, hugs ground pushes under
  warm air
• Warm air moves up, cools, precipitates
• Cool air upper layers move faster due to less
  drag from the ground
• Strong storms- thunderheads
• Weather afterwards is clear, dry, pleasant
• Warm-
• Less dense so will slide up over cool, air
  pockets creating long wedge shaped profile
• Prevents violent updrafts
• Layers of clouds at different levels
• Can bring days of drizzle could skies

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13. Cyclonic Storms

• Low pressure generated by rising warm air
• Winds swirl into low pressure area
• Rising air is full of water vapor
• latent energy released by condensation
  intensifies
• Storm cells will build as this cycle continues

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a. Hurricanes

• Atlantic E. Pacific- hurricanes
• W. Pacific- typhoons
• Indian Ocean- cyclones
• Winds as high as 200 mph
• cause most property damage and loss of life
• begin over warm oceans of the tropics
• solar insolation (water gt80ºF) provides energy
  for huge evaporation, cloud formation, and
  atmospheric lifting

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b. Tornadoes

• swirling masses of air with speeds of 300 mph,
  may have hail
• waterspouts occur over water
• center of tornado is extreme low pressure which
  causes buildings to implode
• Faster moving upper air speeds, lower speeds
  close to ground cause rotation
• destruction is usually less than 0.5 miles wide
  and 15 miles long
• Tornado Alley is from Texas to Indiana
• Cold air from Canada collides with warm air from
  Gulf of Mexico
• Downbursts are less organized air masses but very
  strong

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c. Seasonal Winds

• Monsoon- seasonal reversal of wind patterns
  caused by different heating cooling rates of
  ocean continents
• Cause massive amounts of rain flooding
• Common in India due to Indias geography
• Also in N. Africa

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• CLIMATE
• Pattern of weather in a region over long time
  period

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Climatic Catastrophes

• Can be drastic- (Ice Age) entire communities can
  be destroyed, species can become extinct
• 65 million years ago- Cretaceous- 75 of life
  (including dinosaurs) became extinct due to
  sudden cooling of atmosphere (Sulfur dioxide from
  volcanoes?)
• Can be gradual- allows population to become
  adapted or migrate

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Patterns in Weather Cycles

• Milankovitch cycles- periodic shifts in earths
  orbit and tilt
• Orbit stretches shortens every 100,000 years
• Axis of rotation changes angle of tilt every
  40,000 years
• Axis wobbles like a top every 26,000 years
• These variations change the distribution
  intensity of sunlight
• Evidence of this in sedimentary rock layers

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Patterns in Weather Cycles

• 1400s- little ice age
• Temps dropped, crops failed
• Fish did not migrate north
• People starved or killed by Inuits forced south
  due to cold
• 135,000-115,000 years ago temp. flipped from warm
  to cold over a period of decades instead of
  centuries
• Scientists think might be due to shift in ocean
  currents or dilution of ocean with freshwater
• Or volcanic eruptions

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El Nino Southern Oscillations (ENSO)

• Occurs every 2-7 years
• Occurs when prevailing westerly winds cease or
  slow down allowing surface of ocean to warm up.
• Warmer waters drive schools of fish away
  affecting South American fishermen
• El Nino- means Christ child because it happens
  around Christmas in Peru
• La Nina- means little girl represents time when
  El Nino is not occurring.
• These two cycles are called the El Nino Southern
  Oscillation or ENSO

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How does ENSO affect us?

• Northern jet stream is split drawn over
  Southern U.S.
• This pulls moist air from Gulf of Mexico up
  causing more intense storms heavy rain
• La Nina has opposite effect causing hot, dry
  weather