Download Chapter 5 Clouds

Chapter 5
Clouds
What are the Basic Elements
of Weather & Climate
(list 6)
 Temperature
 Humidity
Clouds
Precipitation
Pressure
Wind
Precipitation
List 6 forms of precipitation:
What is graupel?
Clouds:
• A visible aggregate of minute droplets of
water or tiny ice crystals (or both).
For Clouds to form, TWO conditions must exist:
1. Air is lifted, cooled adiabatically, until the air
is SATURATED. Then water vapor can
condense into water droplets
What do all these pictures have to
do with clouds?
Cloud Condensation Nuclei
2. Water vapor needs to condense (stick) onto
a SURFACE.
A “surface” can be microscopic dust particles,
smoke, salt, pollen, volcanic ash, soot from
combustion or forest fires.
Without the condensation nuclei surface, the air needs to
be greater than 100% humidity or very, very low
temperatures (so the water vapor has very little KE and
the particles can slow down enough to collide and stick
together.
2 types of condensation nuclei
Hygroscopic nuclei
• “Water-seeking”
• Effective sites for water
vapor to condense into
droplets.
• Form larger water droplets
•
•
•
•
• Example: salt particles
Hydrophobic nuclei
“water-repelling”
Not efficient for forming
water droplets
only if the relative humidity
reaches 100%
Form smaller droplets
Initially, cloud
droplet formation is
rapid,
but it slows as the
water vapor in the air
is used up
The size of cloud
droplets can vary.
It takes about a
million cloud
droplets to form a
single raindrop.
Classification
High Clouds
Prefix: ____________
_____________meters
Middle Clouds
Prefix: ___________
____________meters
Low Clouds
Prefix: ____________
_____________meters
Clouds of Vertical
Development
Cloud Types
Height
Composition
Description
Cloud Types: height and form
Pg. 134
Cirrus Clouds
Cirrostratus
Cirrocumulus
Aircraft
Contrails:
Condensation trails of ice crystals
Altocumulus
Altostratus
Nimbostratus
Cumulus Clouds
Cumulonimbus:
Dark, dense,
towering clouds with
anvil-tops that reach
heights of 30,000 ft.
and produce
thunderstorms, hail
and tornados.
• Why are high clouds always so thin
compared to low clouds?
Lenticular
Clouds