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Cloud Formation
I. Cloud Formation
A. Cloud-
A collection of millions of tiny water drops in
the air.
B. Why are there clouds in the sky?
1. Clouds start to form when a parcel of warm
moist air starts to rise.
2. Parcel-
A small contained area of air.
3. As the parcel gets higher it cools and
expands.
4. Cold air cant hold as much H2O as warm air.
5. The parcel will reach saturation eventually.
6. If the parcel of air reaches saturation, H2O
will condense onto any solid object. (Dust, salt,
smoke, etc.)
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7. If the parcel is allowed to keep on rising
millions of H2O drops condense onto this stuff.
8. That is when a cloud is formed.
II. Why do clouds form in certain areas?
A. Air can be stable or unstable.
1. Stable Air-
When a rising parcel of air becomes cooler than
the air around it. .
A.) High Pressure
B.) If the air becomes stable it will sink.
C.) If that happens before the air is saturated,
a cloud will not form.
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2. Unstable Air-
When a parcel of air is warmer than the air
around it.
A.) Low Pressure
B.) If the air stays unstable it will continue to
rise.
C.) If it reaches the saturation level it will
form a cloud.
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III. Cloud Classification
A. There are three main types of clouds.
1. Cirrus
A.) Thin feather like clouds.
B.) High altitude.
C.) No precipitation.
D.) Can be a clue that a storm is approaching.
2. Cumulus
A.) Thick puffy clouds.
B.) Some are cauliflower shaped.
C.) Thunderstorms and hail are come in some
types.
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3. Stratus
A.) Light gray, thin layered clouds.
B.) Low altitude.
C.) Light precipitation in most types.
D.) Fog is an example.
B. Cloud Types
1. There are five words that can be attached to
the main cloud types, to give them a more
specific name.
A.) Cirro-
High altitude clouds.
B.) Alto-
Mid altitude clouds.
C.) Strato-
Low altitude clouds.
D.) Nimbo Nimbus-
Very dark heavy rain clouds.
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C. Examples
1. Cumulonimbus
A.) Cumulus cloud that grew into a very large,
dark, heavy rain cloud.
B.) This type of cloud is the heaviest rainmaker.

C.) Thunderstorms, and tornadoes are common.
2. Nimbostratus
A.) Huge layers of dark., low altitude, rain
clouds.
B. ) Very long periods of rain can fall from
these clouds.
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I. High Clouds
1. Cirrus
2. Cirrostratus
3. Cirrocumulus
II. Middle Clouds
1. Altostratus
2. Altocumulus
III. Low Clouds
1. Stratus
2. Stratocumulus
3. Nimbostratus
IV. Clouds with vertical development
1. Cumulus
2. Cumulonimbus
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IV. Precipitation
A. There are 5 types of precipitation.
1. Rain-
Drops of H2O falling into areas of above freezing
temps..
2. Snow-
H2O that falls as a frozen six sided, flake.
3. Sleet-
Forms when snow falls through a warm area of air,
melts, then freezes back into an ice pellet.
4. Hail-
Warm weather falling lumps of ice.
A.) Most commonly found in cumulonimbus clouds. .

B.) Water freezes in the upper level of the
cloud, into a small ice pellet.
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C. ) When it falls it gets caught in the strong
up drafts of wind.
D.) The up drafts blow the ice pellet back into
the freezing temperatures.
E.) Another layer of ice forms around it.
F.) The process continues until the ice pellets
are too heavy for the up drafts.
G If the ice pellet does not melt before it hits
the ground you will see hail.
5. Freezing rain-
Rain drops that are super cooled.
A.) Salt dissolved in rain lowers the freezing
point of H2O.
B.) As soon as it touches a solid surface it
freezes to it .
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Weather Patterns
I. What causes our weather to change?
A. The movement of different air masses causes
weather to change.
Large body of air that has the same
characteristics as the same area it formed over.

1. Air Mass-
B. There are four basic air massed that effect
weather in United States.
1. Continental Polar (cP)-
Form over cold dry areas.
A.) cP air masses bring clear skies, and cold
temperatures.
B.) Come from Canada.
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2. Continental Tropical (cT)-
Form over warm dry areas.
A.) cT air masses bring clear skies and warm
temperatures.
B.) Come from Mexico.
3. Maritime Polar (mP)-
Form over cold wet areas.
A.) mP air masses bring cloudy skies and cold
temperatures.
B.) Come from the Northern Pacific, or the
Northern Atlantic.
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4.Maritime Tropical (mT)-
Form over warm moist areas.
A.) mT air masses bring cloudy skies and warm
temperatures.
B.) Come from the Gulf of Mexico. (Provides the
majority of moisture to eastern storms)
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Blues cold/dry
Green cold/moist
Pink hot/moist
Red hot/dry
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C. Why do air masses change weather?
1. These four air mass types can be either stable
or unstable.
2. When two different air masses collide weather
changes may occur.
3. The boundary between the two air masses is
called a front.
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II. Fronts
A. What are fronts?
1. Front-
The boundary between two different air masses.
2. If air between the boundaries is unstable then
clouds will form and a storm may occur.
show me
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B. There are four types of fronts
Happens when a warm air mass moves into a cold
air mass.
1. Warm Front-
A.) The warm air will rise over the cold air
slowly.
B.) If the air is wet, clouds of the stratus and
cumulus variety will form.
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C.) If the air is dry it will bring nice weather
with some high cirrus clouds.
D.) On a weather map they look like this
Cold Air
Warm Air
2. Cold Front-
Happens when a cold air mass moves into a warm
air mass.
A.) The cold air forces the warm air to rise
quickly.
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2. Cold Front-
Happens when a cold air mass moves into a warm
air mass.
A.) The cold air forces the warm air to rise
quickly.
B.) Makes the air rise twice as fast as warm
fronts.
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C.) This rapid movement can cuse large rain
clouds if the air is wet. .
D.) Large cumulus and nimbostratus clouds are
common.
E.) On a weather map they look like this.
Cold Air
Warm Air
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3. Occluded Front-
Happen when two cold air masses collide and force
a warm air mass between them to rise.
A.) Very heavy rain will occur if the air mass is
wet enough.
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B.) Cumulonimbus clouds and high winds are
common.
C.) This is the severe weather front.
D.) If air is dry high winds and moderate rain
clouds are still common.
E.) On a weather map they look like this
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Happens when pressure differences cause a warm
front and a cold front to stop moving towards
each other.
4. Stationary Front-
A.) This type of front may stay in the same area
for days.
B.) If the air is wet, light precipitation and
wind can last for as long as the front is
stationary.
C.) Nimbostratus clouds are common.
D. ) If the air is dry light winds and stratus
clouds are common.
E.) On a weather map they look like this

Warm Air
Cold Air