 Cloud Types 
What is a cloud?
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Warm air contains water vapor
The air cools to its dew point
The water condenses and forms either water droplets or ice crystals
To form a cloud it the water must condense around a solid object
– The solids that help create clouds include dust, smoke, salt, or ice crystals
Why are there different cloud types?
• Clouds are not the same because they form under different conditions.
• Different types of clouds are formed depending on how the warm moist air that creates
them rises, small puffy clouds are formed when air rises quickly, over a small area.
Larger flat clouds are formed when warm moist air rises slowly over a larger area.
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What are the different cloud types
There are 3 basic cloud types based on the altitude that they form at.
– Cirrus Clouds, are wispy, feathery clouds that from at higher altitude. They are
usually made of strictly ice crystals. Sometimes called horse tails, and/or fish
scales. These clouds can help predict the weather.
– Cumulus Clouds are fluffy rounded clouds that look like cotton. They form low to
the ground but can grow upwards.
– Stratus Clouds form flat layers, they usually form flat gray layers that cover the
sky.
What are the cloud prefixes?
Along with the names cirrus, stratus, and cumulus, there are other prefixes that are
used to describe cloud types.
These prefixes are,
– cirro, meaning high
– Alto, meaning middle
– Nimbo, meaning rain
– These prefixes are used to describe different clouds that occur at different levels.
What are all the different types of clouds?
High level clouds:
– Cirrocumulus
– Cirrostratus
– Cirrus
Middle level clouds:
- Altostratus
- Altocumulus
- Cumulus
• Low level clouds:
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Stratocumulus
Nimbostratus
Stratus
Cumulonimbus, starts out as a low level cloud and then grows up to the middle
layer.
Which cloud type produces precipitation?
Any cloud with the prefix nimbus produces precipitation.
These include nimbostratus, cumulonimbus
What is precipitation?
There are 4 types of precip.
– Rain - liquid water that falls to the ground
– Sleet - frozen rain droplets that fall to the ground.
– Snow – ice crystals that form flakes that fall to the ground
– Hail – balls or lumps of ice that falls from clouds, they can range in size from a pea
to a softball.
Fronts and Air Masses
Air Masses: An air mass is a large body of air that has similar properties to the area of
the surface that it formed over.
Dry air masses usually form over land, and wetter air masses form over water.
Warm air masses form over the tropics. An air mass that develops over the far
north or south would be cooler.
Air masses can cover thousands of square miles.
Cyclones and Anti-cyclones:
Air pressure varies over the surface, wind blows from high pressure zones into
low pressure zones, in the northern hemisphere when high pressure air blows into a low
pressure zone the coriolis effect causes these winds to turn in a counter clockwise
direction, these large areas turning low pressure areas are called cyclones. Cyclones
usually bring stormy weather
Anticyclones are areas where the wind spirals out of a high pressure zone in a clockwise
rotation. They are associated with fair weather.
Thunderstorms:
Thunderstorms: happen when a cold front moves in under warm moist air. This
movement of air creates cumulonimbus clouds. These very tall clouds (up to 18 km) are
created by updrafts (winds that blow upward); these winds push warm moist air up into
the colder air causing rapid condensation.
T storms create several unique weather phenomena, one of these is hail, the others are
lightning, and tornadoes.
Lightning is created by positive and negative charges created by the movement of water
molecules in the cloud. Positive charges are usually created in the upper part of the cloud
and negative charges are created in the lower part of the cloud. When the charges
become strong enough there is a discharge of electricity.
Lightning can travel from the ground to the cloud, from the cloud to the ground, and from
parts of the cloud to other parts of the cloud.
Types of lightning:
Forked lightning: the typical branched and zigzagged lighting strike we think of.
Sheet lightning: this is lightning that discharges from cloud to cloud, or inside of a cloud:
Heat lightning: can be either forked or sheet lightning. The storm is so far away you
can’t hear the thunder.
Ball lightning: a ball shaped bolt of lightning, this can sometimes be seen near object in
storms, like ship masts, even cattle horns
Thunder: lightning creates thunder. A lightning bolt is about 54,000 degrees F or 5-6
times hotter than the sun! The lightning super heats the air around where it travels. The
air rushes away so fast it breaks the sound barrier, creating thunder.
Lightning safety:
Flash to crash rule, you can tell how far the lighting is from you by counting between
flash and the crash, every 5 secs = 1 mile.
Get indoors or into a car as quickly as possible.
The lighting position: get to the lowest point you get to, (not under tree or rock. Then
crouch down over your feet with you head down between your knees.
Stay off the landline phone, computer, etc during a lighting storm, don’t take a shower
during lighting storms or use the sink or potty during a t storm. As the lightning can jump
through the electrical lines/phone lines, or travel through the plumbing.
Tornadoes
Only 1% of thunderstorms produce tornadoes, these thunderstorms are call supercells
Tornadoes are created inside of cumulonimbus clouds when the air pushed up by updraft
winds begins to sink in different directions creating wind shear. These twisting winds
revolve around the low pressure created by the updrafts. As they gain velocity these
spinning winds begin to form a funnel cloud.
A tornado is formed when the funnel cloud touches down onto the earth’s surface.
75% of tornadoes form in the United States. The Midwest section of the country also
known as tornado ally is where most of these tornadoes are formed. South Dakota,
Nebraska, Iowa, Kansas, Oklahoma, and Texas are the states that make up tornado ally.
Late spring and early summer are the most common times for tornadoes to form.
Tornadoes are measured based on the amount of damage that they do. The fujita scale is
the measurement tool that is used to classify tornadoes. The minimum wind speed for a
F0 is 74 mph, the highest winds for a F5 is over 300 mph.
It is a scale based on six levels
F0 is considered light, broken branches and chimneys
F1 is considered moderate, roof damaged, mobile homes upturned
F2 is considered considerable, roof torn off homes, large tree uprooted
F3 is considered severe, trains overturned, roofs and walls torn off
F4 is considered devastating, houses completely destroyed, car picked up
and carried elsewhere
F5 is considered incredible, total demolition
F6 is considered inconceivable; incredibly unlikely the extent of
devastation would be undistinguishable from the F5 winds that would also
be present
Hurricanes: the most powerful storm on the planet is hurricanes.
Although tornadoes have stronger winds, the size, and destructive potential of hurricanes
make them the number 1 worst storm on the planet.
How hurricanes form:
Hurricanes form off of the coast of Africa in the summer months. The sun gives the
hurricane its energy. Low-pressure systems created by the evaporation of large amounts
of ocean water create bands of cumulonimbus clouds.
High-pressure air tries to push into the low-pressure zone this causes the rain bands to
start to rotate counterclockwise in the northern hemisphere.
This rotation creates the eye of the hurricane; the eye wall is where the strongest winds of
the hurricane are located.
The trade winds push the storm system westward towards the gulf of Mexico as the storm
moves across the ocean it gains strength.
A hurricane starts life as a tropical depression, if it gains wind speed it will become a
tropical storm, if it continues to gain wind speed it will become a hurricanes.
Why hurricanes get names:
When a tropical storm becomes a hurricane it is given a name. The national weather
service names all hurricanes as a way to track them. This started in the 1950’s when
hurricanes received only women’s names. Since then they receive both men’s and
women’s names that follows a rotating list.
Hurricane damage:
When hurricanes travel across the Atlantic they build up energy become stronger. When
they finally hit land they cause damage through three main ways.
Storm surge, as the hurricane move towards land it pushes the ocean water along
with it creating huge waves called storm surge. Depending on the strength of the
hurricane this storm surge can be anywhere from three feet above normal to 8-10 feet.
The areas along the coastline usually are only a few feet above sea level and the storm
surge causes flooding in the low lying coastal areas. This is where most of the fatalities
occur due to hurricanes.
High winds, hurricanes are categorized based on wind speed.
The Saffir-Simpson scale is the measurement tool used to rate a hurricane.
They are rated from category 1 – 5
Category 1 hurricanes have a minimum of 74 mph sustained winds.
Category 5 hurricanes have a minimum of 155 mph sustained winds
Sustained winds are winds that blow constantly.
Katrina was a category 3 hurricane and is estimated to have cost almost 300 billion in
damages to the gulf coast.
Massive Rain fall, hurricanes also cause damage due to flooding. When the storm
makes land fall it releases the large amounts of rain that is stored in the clouds this can
cause flooding to areas that are hit. Hurricanes can also spawn tornadoes that cause even
more damage.