Transcript Clouds Notes

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 Fog
Ground 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