GEOG1- Midterm #2 (Ch. 6 Atmospheric Water)
Terms
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- absolute humidity
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A direct measure of water vapour content of air.
Grams of water per cubic meter of air. - advection fog
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Fog caused by condensation that results warm, moist air moving horizontally over a cold surface.
Example- Fog in SF, warmer air from the ocean blows over the colder water along the coast of SF and cools to the dewpoint, creating clouds that are blown into SF. - cirrus
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-High in the atmosphere
-Thin, wispy since they can't hold much water vapour
-Ice crystals
-Good sign that a storm is coming - condensation
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Process of water vapour being converted into liquid water
Warming process due to latent heat release. - conditional instability
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-When the lapse rate falls between the dry and wet/saturated adiabatic rates.
-Dry:Stable, Moist:Unstable
-Rising air becomes unstable after condesation releases latent heat.
-Ex: Air forced to rise over mountains. - convection uplift
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-Lifting mechanism
-Occurs where there is a hot ground causing the air to rise and expand which cools quickly.
-ITCZ - cumulonimbus
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A cumulus cloud that is capable of producing heavy rain and thunderstorms.
(tall clouds, rising air, vertical) - cumulus
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-Tall clouds
-Vertical
-Rising air - deposition
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Process of water vapour being converted into ice.
(cooling?) - dew
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The condensation of beads of water on cold surfaces.
Occurs due to land radiation, especially at night when the ground and air adjacent is cooled through conduction to the point of saturation. - dewpoint temperature
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The temperature to which you'd have to cool the air to reach saturation.
Higher the dewpoint = More water vapour in the air - dry adiabatic lapse rate
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The rate at which unsaturated air cools while rising.
5.5/1000'
Relative humidity is below 100 - evaporation fog
- Fog caused by condensation that results from the addition of water vapour to cold air that is already near saturation.
- frontal uplift
- A lifting/rising mechanism caused by cold air meeting warm air...cold air forces the warm air to rise causing it to cool.
- hail
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-Pellets of ice
-Produced in cumulonimbus clouds where there are strong updrafts that cause water droplets to get high enough to freeze, then fall back down to gain more water only to get blown back up to freeze again. - latent heat
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Energy given off during state changes.
Ex- Evaporation is a cooling process because latent heat is stored, while Condensation is a warming process since it is given off. - lifting condensation level
- The altitude at which rising air reaches 100% relative humidity or the point of saturation and condensation begins.
- orographic uplift
- A lifting/rising mechanism that occurs when air is forced to rise over a topographic barrier such as a mountain and it cools at it rises.
- evaporation
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Process of liquid water being converted into water vapour.
Cooling process because latent heat is stored. - radiation fog
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Fog caused by condensation near the ground where the air cools to the point of condensation because of contact with the cold ground.
-Long, cold winter nights
-Worse after a winter storm
-Once it becomes big enough, it can preserve itself
-Ex: Tule Fog - rainshadow
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Drier condition on the other side of the mountain so there is less rainfall.
Occurs because the air descends and warms adiabetically
(Donner Summit --> Reno) - relative humidity
- Ratio (percentage) of the amount of water vapor in the air compared to the maximum possible (saturation) at that temperature.
- saturated (wet, moist) adiabatic lapse rate
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The rate of cooling once the air reaches the point of saturation as it rises.
Less than the dry - sleet
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Raindrops that freeze while falling to the ground
East Coast - snow
- Solid precipitation in the form of ice crystals which are formed from the direct conversion of water vapor into ice. (deposition)
- stratus
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-Low clouds that blanket the sky
-Drizzle, showers
-Thin layers
-Nimbostatus=rain, capable of producing drizzle - sublimation
- Process of ice being converted into water vapour
- upslope fog
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(Orographic fog)
Fog that occurs due to condensation that results when humid air is forced over a mountain and cools adiabatically.
-Ex: Highway 88, moist air coming off the ocean is forced to rise over the Sieeras and as it cools, fog forms. - water vapor
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-The gas state of water.
-Very important in the atmosphere.
-Can move and mix freely