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Water phases transition
to change from one state to another; heat must be absorbed or released.
- water, ice, and water vapor
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Saturation
-balance between water vapor molecules leaving the surface and those returning to the surface.
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Relative humidity
- ratio of air's actual water vapor content compared with the amount of water vapor required for saturation at that temperature- and pressure
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Dew point temperature
- -temperature needed to cool air to reach saturation
- - causes water vapor to condense forming
- -dew, fog, or cloud formation
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variations in temp and relative humidity
- increasing temps: lower relative humidity
-decreasing temps: higher relative humidity
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Dew point is temperature of saturation...
-high dew point temp: moist air
- low dew point temp: dry air
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4 lifting mechanisms that lifts air
- Orographic lifting
- frontal wedging
- convergence
- localized convective lifitng
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(mechanisms that causes air to rise) Orographic lifting
-air is forced to rise over a mountain
- - adiabatic cooling generates clouds, precipitation
- -leeward side of it, rainshadow desert
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(mechanisms that causes air to rise) Frontal wedging
- - cool, dense air acts as a barrier to warm, less dense air.
- -forces warm air to rise, typical in North America
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(mechanisms that causes air to rise) Convergence
- - air converges from more than 1 direction
- -forces air upward
- - change in surface texture can "pile up" air
- -ocean wind converging onto land
- -rougher land forces the air to converge
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(mechanisms that causes air to rise) Localized convective lifting
- -unequal surface heat causes localized pockets of air to rise
- -creates thermals
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stable air vs unstable air
- -stable air resists vertical displacement
- - cooler, denser than surrounding air
- -wants to sink
- - unstable air
- - warmer air, less dense than surrounding air
- -tendency to rise
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dry adiabatic rate
- unsaturated air
- -rising air expands and cools
- -10 C per 1000 meters
- -descending air is compressed and warms
- -10 C per 1000 meters
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Wet adiabatic rate
- - commences at condensation level
- - air has reached the dew point
-condensation occurring, latent heat is liberated
- -heat is released as water condenses
- - 5-9 C per 1000 m
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3 different forms of clouds
-Cirrus
-Cumulus
-Stratus
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(forms of clouds) Cirrus
high, white, thin
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(forms of clouds) Cumulus
globular, individual cloud masses
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(forms of clouds) Stratus
sheets or layers that cover much of the sky
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(types of clouds) High clouds
-above 6000 meters
- -thin, white, made of ice crystals
- low temps, little water vapor
- cirrus
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(types of clouds) middle clouds
-2000 to 6000 meters
-infrequent light snow or drizzle
-altocumulus
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(types of clouds) low clouds
-below 2000 meters
-stable conditions, produces precipitation
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3 types of fogs
- advection fog
- radiation fog
- upslope fog
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(fog types) Advection fog
-warm, moist air moves over a cool surface
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(fog types) Radiation fog
- earth's surface cools rapidly
- forms during cool, clear, calm nights
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(fog types) Upslope fog
humid air moves up a slope
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2 evaporation fogs
fogs resulting from addition of water vapor
-steam fog
-precipitation fog
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(evaporation fogs) Steam fog
- cool air moves over warm water, moisture added to air
-water has a steaming appearance
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(evaporation fogs) Precipitation fog
-frontal wedging when warm air lifted over colder air
-rain evaporates to form fog
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latent heat
-energy released or absorbed during a change of state
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Forms of precipitation
- Hail
-Rime
-rain or drizzle
-snow
-sleet and glaze
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(forms of precipitation) Hail
- they come from large cumulnonimbus clouds
-updrafts that occur carry the ice higher, the higher its carried the bigger hail
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(forms of precipitation) Rime
- deposit of ice crystals from freezing of supercooled fog or cloud droplets on surfaces below freezing
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(forms of precipitation) Rain or Drizzle
- typically in nimbostratus clouds
drizzle: stratus or nimbostratus clouds
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(forms of precipitation) Snow
precipitation in form of ice crystals
size, shape vary by temps
- -Warmer temps: composite snowflakes
- -heavy, high moisture content
- - Cold temps: low moisture content
- -light fluffy snow
- - 6 sided crystals
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(forms of precipitation) Sleet
-occurs when warmer air overlies colder air
-rain freezes as it falls
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(forms of precipitation) Glaze
-subfreezing air near ground
-raindrops become supercooled during fall thru cold air
-turn to ice upon colliding with solid objects
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