What is weather?The state of the atmosphere at a given time and place.
ex. Partly cloudy with 50% chance of rain today
Typical patterns over a period of years in a given location
ex. Temperate climate
Then, what is climate?
What gases make up the atmosphere?
• 78% nitrogen• 21% oxygen• 1% other• argon, carbon
dioxide, helium, hydrogen, neon, water vapor, dust
Troposphere (0-18km)
• Closest to Earth• Layer in which almost all weather occurs• Nearly all CO2 and H2O vapor found here
Tropopause • Temp. remains nearly constant –55oC• Clouds in this region consist mainly of ice
Stratosphere (20-50km)
• Very little H20 vapor and dust
• Contains ozone layer• Protects humans and all other organisms
by absorbing UV rays
• Super Sonic Jets fly in this layer
Mesosphere (50-80km)
• Coldest layer of the atmosphere
Thermosphere (80-500km)
• Hottest layer of the atmosphere– Few molecules but, the molecules absorb
Sun’s UV rays and heat up individual molecules
Ionosphere (65-500km)• Atoms become charged due to intense
radiation• Located within the ThermosphereExosphere• Outermost layer of the atmosphere• Gradually fades out into space
Exosphere• Outermost layer of the
atmosphere• Gradually fades out into
spaceIonosphere (65-500km)• Atoms become charged
due to intense radiationThermosphere (80-500km)• Hottest layer of the
atmosphereMesosphere (50-80km)• Coldest layer of the
atmosphere• Extremely high winds• Jet stream – airplanes fly
here
Stratosphere (20-50km)• Very little H20 vapor and dust• Contains ozone layer• Protects humans and all other
organisms by absorbing UV raysTropopause • Temp. remains nearly constant –
55oC• Clouds in this region consist
mainly of ice• As you move away from the
Earth, the temp. in each layer changes
Troposphere (0-18km)• Closest to Earth• Layer in which almost all weather
occurs• Nearly all CO2 and H2O vapor
found here
OZONE LAYER
• The sun produces many types of radiation, including light and ultraviolet (UV) rays
• UV rays can cause skin cancer if we receive too much
• Ozone layer protects us from most of the harmful rays by absorbing 99% of UV radiation
• BUT…….• The ozone layer is thinning
b/c we use CFC’sCHLOROFLUOROCARBONS• CFC’s are used as coolants
in refrigerators, air conditioners; propellants (think of aerosol hairsprays); and in making foam
• Why are CFC’s so bad?
OZONE LAYER
• Here’s what happens when CFC’s get into the ozone layer….
• NORMALLY… UV rays break down ozone, which can reform under normal conditions and absorb more UV rays GOOD
• BUT… CFCs prevent ozone from reforming; Cl atom can destroy thousands of ozone molecules.
Heat & Temperature Changes in the Atmosphere
• Changes in weather involve air movements, formation of clouds, and precipitation.
• Energy is needed to make these things happen.
• The energy comes from the SUN.
Heat & Temperature Changes in the Atmosphere
3 Ways to Transfer Heat…
RADIATION• Transfer of heat energy in waves
(infrared waves or light)• Ex. Your head gets hot when you
sit by the pool in the summer as it absorbs the sun’s energy
Heat & Temperature Changes in the Atmosphere
CONDUCTION• Transfer of heat through direct
contact• Ex. Your feet get hot when you
stand barefoot on a hot sidewalk
Heat & Temperature Changes in the Atmosphere
CONVECTION• Transfer of heat through
currents in heated material• Only occurs in liquids and gases• Ex. Cooking rice on a stove
CONDUCTION
CONVECTION
RADIATION
The Wonderful GREENHOUSE EFFECT
• The atmosphere acts like a blanket to keep in the sun’s warmth
• If we didn’t have our atmosphere, it would be 400oF (200oC) during the day, and -420oF (-250oC) at night!
• GREENHOUSE EFFECT: trapping of the sun’s energy by the atmosphere
• Several gases are responsible for this effect…– Carbon dioxide (CO2)– Water vapor– Nitrous oxide (N2O)– Methane (CH4)– Chlorofluorocarbons (CFC’s)
The Wonderful GREENHOUSE EFFECT
• Unfortunately, greenhouse effect is increasing due to… – burning of fossil fuels– industry waste
Why is this considered a bad thing?• A warmer atmosphere could…• melt the ice caps of the worldraise sea levels and flood coastal areas around
the world shift rainfall patterns around the world
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