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Clouds
Clouds are categorized by
their shape, altitude and the
weather associated with them.
Cumulus
• Thick, puffy clouds
with vertical
development.
• May grow to great
heights.
• Fair weather clouds
unless they grow
vertically.
Stratus
• Low lying gray layered
clouds
• Often associated with light
precipitation
• Fog is a ground level
stratus cloud
• Can bring long periods of
rain depending on the
direction that they come
from (NE to S)
Cirrus
•
•
•
•
High Altitude
Thin, wispy clouds
Made of ice crystals
Fair weather clouds if they
come from the west,
northwest or north.
• Harbingers of
precipitation within 20-30
hours if they come with
steady winds from north,
northeast, or south.
Cumulonimbus
• Storm clouds associated
with thunderstorms,
hailstorms and can
develop tornados if all
conditions are right.
• From underneath, they sky
will appear very dark as
little light can penetrate
through them.
• Can reach heights of
several miles.
Cloud Prefixes/Suffixes
• Cirrus or Cirro means high clouds –
examples are cirrostratus or cirrocumulus
• Alto means mid level clouds 8,500-20,000
feet. Examples are altostratus or
altocumulus
• Nimbo or nimbus means precipitation
cloud. Examples are nimbostratus or
cumulonimbus
How do clouds form?
• Moisture (water vapor) in the air condenses (turns
into liquid) into tiny water droplets.
• Condensation occurs on tiny particles of dust
called condensation nuclei
• The steepness of the slope of warm, moist air
being forced upward can determine the type of
clouds that will form and whether or not their will
be precipitation.
• The rule – The more moisture and the steeper the
slope, the more likely the chance of precipitation.
What causes precipitation?
• Warm, moist tropical air collides with cold, dense
polar air.
• The result is always the same. The warm moist air
is less dense, so it will rise above the cold, more
dense air. This rising and subsequent cooling
causes condensation to occur and as water droplets
collide with one another, they get larger and larger
until upward blowing winds cannot keep them
suspended, and they fall.