Chapter 18
• Characteristics of
water…
• Frozen water = ice
• Liquid water = water
• Water as a gas =
water vapor
• Melting
• Evaporation
• Condensation
• Sublimation
• Deposition
• Freezing
• Ice to water
• Water to water vapor
• Water vapor to water
• Ice to water vapor
• Water vapor to ice
• Water to ice
• Humidity
• Specific humidity
• Relative humidity
• Water vapor in
the air
• The grams of
water in the air
(not really used)
• The % of water
vapor in the air
• If the humidity is
50%………
• Warm air holds
MORE moisture
than cold air
• Then the air is
“holding” 50% of
what it can
possibly hold
• What happens at
100% humidity?
• Condensation
(NOT RAIN!!!)
• Psychrometer
• Measures the
humidity in the
air
• Dew
• Dew Point
• Water vapor that
has condensated on
the ground
• The temperature at
which the air can no
longer “hold” the
water vapor and it
condenses on the
ground
• Condensation
nuclei
• Dust or small
particles floating
in the air that
water vapor will
condense on
…helps to form
fog
• Frost
• When the dew
point is below
freezing, water
vapor DEPOSITS
on the ground as
frost………..it is
not frozen dew
• Sublimation………
• When there is
frost on the
ground and the
temperature rises
above freezing,
the frost
SUBLMATES
straight to water
vapor
• Fog
• Radiation fog
• Advection Fog
• A low cloud
• Clear night, warm
ground loses heat to
the cool
air……especially
over a body of water
• Moist, warm air
blows over a cool
surface (like a fog
over snow)
18.2 – Types of Clouds
• Clouds
• A collection of cooled
water at any level of
the troposphere
•
•
•
•
Stratus
Cumulus
Nimbus
cirrus
•
•
•
•
Sheets/layers
Puffy
Rain
Wispy/horse tails
(very high and mostly
ice)
• cumulonimbus
• Thunderstorm cloud
• Anvil shaped
• Formation of clouds
occurs at the
condensation level….
• Air is cool enough for
the water vapor to
condense and begin to
form clouds
18.3 Precipitation
• Rain
• Hail
• Freezing Rain
• Sleet
• Snow
• Water
• Only from t-storm
clouds (Ice)
• Rain that freezes when
it contacts the earth’s
surface
• Ice
• Crystallized water
Windward vs. Leeward
• Windward
• Leeward
• Rising airs cools,
condensates in a
clouds then
precipitates………….
• Dry - desert