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