1. dust -- anthropogenic or natural?
   • Maricopa County air quality
   • "fugitive dust"?
2. smoke -- anthropogenic or natural? ( wildfires)
3. pollen
4. exhaust
5. volcanic eruptions
   • Water vapor #1; carbon dioxide #2; sulfur dioxide #3
   • aid in destruction of ozone & creation of acid rain
   • Pinatubo (1991) = 20M tons of SO₂
   • Kilauea Volcano = 1500 tons of SO₂ daily

1. air pressure / barometer
   • pressure decreases with increased altitude
2. compressibility

A.   Hydrogen / Helium

B.   Volcanic Activity (emits: H₂O, CO₂, N, etc.)

III.   STRUCTURE OF THE ATMOSPHERE

complete diagram

A. Defined by Gaseous Composition

1. homosphere
2. heterosphere

• "Clear" Radio Stations

1. density = # of molecules in given volume of air
   • d = mass/volume
   • normal sea level density = 1.2 kg/m3 or 1.2 oz/ft3
2. pressure = molecules bump into each other = push = pressure
   • p = force/area
   • normal sea level pressure = 14.7 lbs/in2
   • normally expressed in millibars = 1013 mb
   • sometimes in inches of mercury = 29.92 in.
   • Demos: glass of water ... crushing a barrel
3. temperature decreases with altitude
4. layers defined by temperature profile
   • troposphere -- where weather occurs
   • stratosphere -- "temperature inversion"
   • mesosphere -- density/pressure very low!!
   • thermosphere

A. Temperature Controls

1. Altitude
2. Latitude (U.S.)
3. Land / Water Relationship (continentality)
4. Oceanic Circulation (ocean currents)

1. Atmospheric Circulation (wind)
2. Topographic Barriers   (*Hawaii)

ATMOSPHERE CHAPTERS ----->

Atmosphere

Temperature / Energy

Seasonal Variations