Types of Clouds
What is a cloud?
~ It is a thick mass of suspended water drops or ice
crystals.
What do clouds tell us?
~ The presence of clouds in the sky is one type of
signal to meteorologists that there will be changes in
the weather. Predicting the weather requires the
understanding of the different types of clouds
Identifying Clouds
To better communicate and understand the many cloud forms in the
sky, meteorologists identify clouds based on five basic cloud
characteristics:
1. The altitude at which they occur
2. Color
3. Density
4. Shape
5. Degree of cover.
From this information, we can identify three basic cloud types and
seven other common cloud types.
Cloud Type by Form
• Clouds can be classified by some simple, but
subjective, criteria that also provides
information on the atmospheric conditions
• One form of classification is based on
appearance or form. Using these
characteristics you can identify the three basic
cloud types: stratus, cirrus, and cumulus
Stratus Clouds
Stratus clouds are thin, sheet-like clouds. They are
layered with some rippling, and cover large portions of the
sky. They are frequently gray and thick. Stratus clouds
are formed when air is forced up slowly.
• The word stratus comes from Latin, means “to spread
out”.
• Stratus clouds are usually low clouds seen on an
overcast day.
• Stratus clouds often block out the sun.
• Some stratus clouds can bring rain
• Usually produce light to heavy continuous rain.
• Fog can be considered a low stratus cloud in contact
with the ground. When the fog lifts, it usually
becomes true stratus.
Cirrus Clouds
• Cirrus clouds are
thin, white clouds
with a feathery
appearance.
• They are the highest
of all clouds
forming at heights
of 30,000 feet or
more above the
earth's surface.
• Cirrus clouds are formed by ice crystals.
• They generally occur in fair weather and point in the
direction of air movement at their elevation. Cirrus
clouds are usually the first sign of an approaching storm
• Cirrus clouds are high, thin, wispy, and feathery.
•Cirrus is a Latin word that means “curl of hair” or wisp of
hair
•Typically found at high altitudes.
Cirrus Cloud Phenomenon
Cumulus Clouds
• Cumulus clouds are flat-
based, billowing clouds
with vertical doming.
Often the top of cumulus
clouds have a
"cauliflower-like"
appearance. Cumulus
clouds are most
prominent during the
summer months.
Cumulus clouds are large,
Cumulus or fluffy clouds
rounded, fluffy, cottony-
form when air is forced up
looking clouds. Cumulus
rapidly and therefore rises
means heap or pile
higher
• Cumulus clouds are associated with thunderstorms.
• These are called cumulonimbus clouds, nimbus means “rainy
cloud
Cloud Type by Altitude
Clouds can also be classified based on their altitude
There are three categories of cloud heights:
1. High Clouds = Cirrus
2. Middle Clouds = Alto
3. Low Clouds = Stratus
HIGH CLOUDS - CIRRO
High clouds: 7-18km
Cold: less than 25oC & made up of ice crystals
Cirrostratus
High Level
• Cirrostratus: high, wispy clouds. They give the
sky a milky white appearance.
• thin sheet-like clouds, cover entire sky, sun &
moon can be seen thru them
Cirrocumulus
High level
• Delicate clouds appearing in bands or
ripples across the sky. They are one of
the least common of the cloud types.
• This small rounded white puffs, has
small ripples often resemble scales
from fish-thus a sky with cirrocumulus
clouds is referred to as a “mackerel sky
Middle Clouds- Alto
Middle level clouds: 2-7 km
0-25oC & composed of both water and ice crystals
These clouds usually form from the gradual lifting
of air in advance of a cold front.
Altostratus
Middle Level
• Altostratus: thin, layered clouds that are blue-gray
or whitish in color and often cover large portions of
the sky. They are thinner if formed at higher
altitudes but are heavier and more dense if closer to
the ground
• cover entire sky, often form ahead of storms
Altocumulus
Middle Level
• oval or eliptical in shape, and can have
gray undersides. They often have a
"cottonball-like" appearance
• have water droplets, appear as grey
puffy masses, rolled out in waves or
bands
• The presence of altocumulus clouds on
a warm and humid summer morning is
commonly followed by thunderstorms
later in the day.
* Picture of altocumulus clouds taken by
satellite
Strato- Low
Low level clouds: 0 - 4 km
Greater than 5oC & composed of water
• Low clouds are of mostly composed of water
droplets. However, when temperatures are cold
enough, these clouds may also contain ice particles
and snow.
• Stratus clouds resemble fog, but they do not reach
the ground. They often produce mist or drizzle
Stratus
Low Level
Dense, uniform dark gray layers.
Stratus clouds resemble fog, but they do not
reach the ground. They often produce mist or
drizzle
cover entire sky, resemble fog, no
precipitation, but can drizzle
Stratocumulus
Low Level • groups of dense, puffy
clouds that cover the sky in dark heavy
masses, long and gray. The often form in
bands across the sky.
• Only light precipitation, generally in the
form of drizzle, occurs with
stratocumulus clouds
Nimbostratus
Low Level
• dark grey, wet looking, associated with
continuous light to moderate falling rain
or snow
• They are dark gray with a ragged base.
Nimbostratus clouds are associated with
continuous rain or snow. Sometimes they
cover the whole sky and you can't see the
edges of the cloud
Fog
Low Level
• Clouds at ground level
Radiation fog: forms at night when cold ground cools the air
above it (in valleys)
Advection fog: forms when warm, moist air moves over colder
surface and cools (in coastal areas)
In this fog, off the coast of Oregon, a cold ocean current cools the air to the
air’s dew point temperature. This cooling of the air created the fog. This is
called:
For the development of this fog, warm water is evaporating into cool air. The cool air becomes
saturated (its relative humidity becomes 100%) and condensation creates the fog. This is called:
Radiation Fog
Cold Air
Condensation
Evaporation
Warm Water
Vertically Developed Clouds
• Fair weather cumulus have the
appearance of floating cotton and have a
lifetime of 5-40 minutes. The cloud tops
designate the limit of the rising air.
Vertically Developed Clouds
• Harmless fair weather cumulus can
later develop into towering
cumulonimbus clouds associated
with powerful thunderstorms.
• thunderstorm clouds, continue to
grow vertically, lightening, thunder,
and tornadoes are associated with
these clouds
Cloud Type by Rain
• Finally, we can classify them based on the presence of rain
• Nimbus: any cloud that rains
Cumulonimbus: taller, towering versions of Nimbostratus:
Nimbostratus: low,
low, flat
flat clouds
clouds that
that are
are often
often
cumulus clouds. Their height can be from associated
associated with
with steady
steady precipitation
precipitation and
and occur
occur in
in
two to five miles. These clouds often form thick,
thick, continuous
continuous layers
layers and
and are
are often
often dark
dark gray
gray
thunderstorms. in
in color.
color.
Remember!
Cirrus clouds are high, white, and thin
Cumulus clouds consist of rounded
individual cloud masses, they normally have
a flat base and the appearance of rising
domes or towers
Stratus clouds are sheets or layers that
cover much or all of the sky
There are three levels of cloud heights: high,
middle, and low
Remember!
High clouds Middle clouds Low clouds
Cirrus Altocumulus Stratus
Cirrostratus Altostratus stratocumulus
Cirrocumulus nimbostratus
All high clouds are thin cause infrequent light Nimbostratus clouds are
and white and are often snow and drizzle the main precipitation
made up of ice crystals makers
Vertical development clouds have their bases in the low height
range, but extend through the middle or high altitudes
Cumulonimbus may produce rain showers or thunderstorms
