 Water
vapor is the source of
all condensation and
precipitation
 Essentially all water on Earth
is conserved –> water cycle
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Changing states requires energy
transfer in the form of heat
Water has a high Specific Heat
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Which means a large amount of energy
is gained or lost as water changes
temperature
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The addition of heat:
 Melting
 Evaporation
 Sublimation – solid directly to gas
The removal of heat
 Freezing
 Condensation
 Deposition – gas directly to solid
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Saturation – the maximum quantity
of water vapor air can hold at a
given temperature and pressure
Warm air can hold more water vapor
than cool air
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Ratio of the air’s actual water vapor
content compared with the amount of
water air can hold at that temperature
and pressure
2 ways to change RH
 1. Add or remove water vapor
 2. Change the temperature
 Higher temp: ________________
 Lower temp: ________________
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Once air is saturated further cooling
causes condensation (ex: dew, clouds)
Condensation nuclei: tiny bits on which
water condesates (dust, smoke, salt)
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Measured using a psychrometer
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Dew Point –Temperature to which air
would have to be cooled for saturation to
occur
Depends on? __________________
For every 10° C increase in temp. the
amount of water vapor for saturation
double
 High dew points indicate moist air
 Low dew point indicate dry air

Dew point can found by using the RH
 When air temp. and dew point are
close: RH is high
 When air temp. and dew point are far
apart: Rh is low

-When air expands: ______________

-When air is compressed: ________
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Orographic: elevated terrains such as
mountains act as barriers to air flow
Frontal Wedging: warmer, less dense air
rises over colder, denser air
Convergence: when air flows in from
multiple directions, lifting results
(Ex. Florida)
Convective: unequal heating of earth’s
surface creates ‘pockets’ of rising air
(parking lots)
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Stable air remains in its position
Unstable air tends to rise
Most stable occurs with a temperature
inversion which means air temp increases as
you go up in altitude
Stability & Weather:
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Stable air: _________________________________
Unstable air: ________________________________
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Classified based on form and height
Cirrus: high, white, thin
Cumulus: rounded with flat base
Stratus: sheets or layers of clouds
Nimbus: rainy clouds

Combinations of these are used to describe any
cloud (Cumulonimbus= ____________________)
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Occurs when temp. drops below Dew Point
Warm air moving over cold surface
Cold air moving over warm water
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Cloud droplet less than 20 micrometers across
Must grow a million times larger to rain
Most precipitation starts as SNOW
Sleet: melts then refreezes closer to ground
Freezing rain: is sleet that hasn’t refrozen
Hail: Balls of ice from thunderstorms