Download Chapter 11 Notes

Atmosphere
Chapter 11 Notes
Composition of the Atmosphere
• Currently:
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Nitrogen (N2): 78%
Oxygen (O2): 21%
Argon (Ar)
Carbon dioxide (CO2)
Water vapor (H2O)
• In the past :
– Helium, hydrogen,
methane, ammonia
Variable Atmospheric Components
• The following gases change over time:
– Water vapor
– Carbon dioxide: increase from 0.028% to 0.039%
– Ozone
• Upper atmosphere: protection from ultraviolet radiation
• Lower atmosphere: pollutant
– Particles:
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Dust
Salt
Ice
Fungi
Bacteria
Atmospheric Layers
• Troposphere
– Weather
• Stratosphere
– Ozone layer
• Mesosphere
• Thermosphere
• Exosphere
– Transition between
atmosphere and
space
Thermal Energy Transfer (Heat)
• Radiation: transfer of heat by electromagnetic
waves (example: heat lamp)
– Visible and infrared EMR is absorbed and reflected by
clouds, atmosphere, and Earth’s surface
– Rate of absorption varies from place to place, and
seasonally
• Conduction: heat transferred through direct
contact
• Convection: movement of heat through currents
in a liquid or gas
Radiation of Thermal Energy
Temperature and air pressure in the
atmosphere
• Temperature = average kinetic energy of
particles in a material, measured in ⁰C, ⁰F, or K
• Temperature increases if pressure is increased
• Pressure increases if density is increased
• Density decreases if temperature increases
– Hot air rises
• Adiabatic heating and cooling: Air changing
temperature without being heated or
cooled—by changing pressure
Temperature Inversion
• Rapid cooling of land on
a cold, clear night can
cause a temperature
inversion
• Temperature inversions
can cause fog, haze, and
smog
• Air pollution is trapped
under the inversion
layer
Wind
• Air moves from high pressure to low pressure:
wind
• Pressure differences are caused by unequal
heating and cooling of different regions
• Friction causes wind to slow down near
Earth’s surface
• Wind speeds increase at higher altitudes
Humidity
• Amount of water vapor relative to the amount
needed to reach saturation
• The dew point is the temperature to which air
must be cooled to reach saturation
Cloud Formation
• Rising air cools, causing water vapor to
condense
• Condensation nuclei (dust, ice, salt, or other
solid particles) must be present for water
droplets to stick to
• Rising air is unstable
• Sinking air is stable (fair weather)
Clouds form from rising air
Types of Clouds
Types of Clouds
• High clouds (ice crystals):
– Cirrus: wispy horse tails
– Cirrostratus: fish scales
• Middle clouds:
– Altocumulus: wavy rows or masses
– Altostratus: thin layered sheets
• Low clouds:
– Cumulus: puffy
– Stratus: layers
Types of Precipitation
• Rain, snow, sleet, and hail are four main types
of precipitation.
• Droplets in clouds grow through the process
of coalescence when droplet collide and stick
together, forming rain drops
• Hail forms when droplets move up and down
through freezing and non-freezing air