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?

• Psychrometer

• Condensation (NOT RAIN!!!)

• 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