Chapter 17
The Atmosphere
• Composition of the
Atmosphere
• 78% - Nitrogen
• 21% - Oxygen
• 1% - Argon, CO2, etc.
Water Cycle
• Evaporation &
transpiration
Condensation 
precipitation
• Water is neither
created nor destroyed
• Photosynthesis
• Respiration
• Plants! Take in CO2,
Water and sunlight to
release O2
• Mammals!Take in O2,
water and food to
release CO2
17.2
Movement of Heat in the
Atmosphere
• Conduction
• Convection
• Radiation
• Direct contact
• Currents
• Transfer of heat
through visible light
(SUN!!!)
• Temperature
• The measure of HEAT
in the atmosphere
Structure of the Atmosphere
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Where all weather occurs;
where we live
• O3….Ozone layer (protects us
from UV light) CFC’s
destroy Ozone!
• 3rd layer
• Magnetic field (ionosphere) –
Auroras!
• CFC’s are
chlorofluorocarbons that
EAT ozone!
Temperature Variations
• Insolation
• Intensity of insolation
• Incoming Solar
radiation
• Higher angles received
less direct sunlgiht
• That is why the poles
are cold and the
equator is always so
warm
• Time of Day…..
• What is the warmest
time of day???
• What is the coldest
time of day??
• Takes a while for the
earth to heat up and
cool down every day
• 3pm
• 3am
• Latitude….
• Higher latitudes tend
to be colder b/c they
have less direct
sunlight
• Closer to the equator
tends to be warmer b/c
there is more direct
sunlight all year long
• Time of year…..
• Tilt of the
earth…………..
• Tilted away from the
earth means less direct
sunlight - colder
• Cloud cover………
• Clouds block the sun
……temperature is
cooler
HEATING OF LAND AND
WATER
• Land heats up and
cools down FASTER
than water.
WHY!????
• Land is a solid!!
• Therefore water heats
up and cools down
SLOWER because it
is a liquid.
• That is why the oceans
are warmest in the fall
and coldest in the
spring