CLOUDS. * Form of condensation * Visible chunks of small water droplets or ice crystals * Good...
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Transcript of CLOUDS. * Form of condensation * Visible chunks of small water droplets or ice crystals * Good...
CLOUDS
* Form of condensation
* Visible chunks of small water droplets or ice crystals
* Good indicators of what’s going on in the atmosphere
Conditions necessary for clouds to form
1. Condensation Nuclei –small, solid particle in the atmosphere that provide a surface that water vapor can condense on. (smoke, dust, ice)
2. Saturated air at its dew point
Convective Cooling (Adiabatic Cooling)
• Air rises and expands.
• This cools the air below the dew point and it condenses.
Forceful Lifting
• Air is forced upward when it hits a slope.
• It rises, expands, cools and condenses into a cloud.
Temperature Change
• Two air masses mix and cool below the dew point and condense.
Classified by form and altitude
Root names:•Cirrus: feathery/fibrous•Stratus: layered•Cumulus: piled up•Alto: middle•Nimbus: rain
Stratus
• Flat base• Very low• Cover large areas• May block sun• Very little precipitation
Nimbostratus
• Large, thick, grey patches
• Block out sun• Continuous rain or snow • Storm clouds
Altostratus
• Thin, gray fibers• Sun shines through• Rain or snow of long duration.
Cumulus
• Fluffy cotton balls• White tops & dark bases. • Fair weather
Altocumulus
• Flat bottomed gray/white • Begin at middle altitude• Possible rain & storms
Stratocumulus
• Low, lumpy layer• Forms as rolls or waves
Cumulonimbus
• Anvil shape at top • Dark base• T-storms & heavy rain/possible hail. Summer clouds.
Cirrus
• Delicate• Wispy, feathery• Tiny ice crystals• Fair weather clouds.
Cirrocumulus
• thin, white rippled layers
• tiny ice crystals• mackerel sky• fair weather• thicken if storm’s coming...
Cirrostratus
• tiny ice crystals• shapeless white veil “milky,”
• do not block sun• rain within 24 hrs
CONTRAILS
KELVIN-HELMHOLTZ: caused by winds being deflected up & over a barrier (such as a mountain), causing a wave-like cloud structure
LENTICULAR: form downwind of an obstacle in the path of a strong air current.
MAMMATUS: sinking air within a cloud
Radiation FogGround cools off at night
Air touching ground becomes cooled to the dew point and condenses
“Burned away by sun as it warms up
Advection Fog
• Warm, moist air moves over a cool surface and forms a thick fog
• Common along coasts
Upslope Fog
• Humid air rises up an incline cools off and condenses into fog.
Steam Fog
• Shallow layer of fog• Forms when cool air moves over inland warm body of water