Cloud Identification
By: Jackie Dye, Johnni Ernst, Tammy Weeks & Cheryl Wilhoit
https://www.youtube.com/watch?v=FMagDRCpJ14
EMPACTS Project, Spring 2014
Introduction to Physical Science
C. Dianne Phillips, Associate Professor of Science and Mathematics
Clouds: What are they?
 Water has a unique trait. It has the ability to change
from a vapor to a liquid to a solid and back again!
 When water changes form, scientist say that "it
changes phase.”
 A cloud is composed of tiny water droplets (or ice
crystals) that are suspended in the air.
 If the droplets become large enough, they may be
visible as a cloud or fog.
 They may also fall to Earth in the form of rain (or snow).
Clouds Continued
•
Clouds are made of water vapor but
condensation plays an important role
in making clouds visible.
•
The drops are small enough to
stay trapped in the air until
condensation reaches a point of
no return, making rain.
•
Water vapor is invisible but
condensation is what makes water
vapor visible.
•
One result of this is that light
becomes reflected and refracted.
This is what makes clouds visible.
•
High temperatures excite water
molecules until they change from a
liquid state to a gaseous one.
•
Clouds are visible because of
colder temperatures in the upper
atmosphere.
•
Lower temperatures can cause
enough water vapor to condense back
into liquid form.
•
•
This small amount stays as very small
droplets that can stay suspended in
the air because small dust particles
attach themselves to them.
In the upper reaches of the
atmosphere, the temperatures are
much colder. This means that
water vapor once condensed can
no longer return fully to its gas
state. Since temperatures don’t
change in this region clouds are
able to keep shape longer.
Cloud Classification
 Clouds are classified according to their height above and
appearance (texture) from the ground.
 The following cloud roots and translations summarize the
components of this classification system:
 Cirro-: curl of hair, high.
 Strato-: layer.
 Cumulo-: heap.
 Alto-: mid.
 Nimbo-: rain, precipitation.
High-level Clouds
 High-level clouds occur above about 20,000 feet and
are given the prefix "cirro-".
 Due to cold tropospheric temperatures at these levels,
the clouds primarily are composed of ice crystals, and
often appear thin, streaky, and white
 The three main types of high clouds are cirrus,
cirrostratus, and cirrocumulus.
Mid-level Clouds
• The bases of clouds in the middle level of the troposphere,
are given the prefix "alto-.”
• They appear between 6,500 and 20,000 feet.
• Depending on the altitude, time of year, and vertical
temperature structure of the troposphere, these clouds may
be composed of liquid water droplets, ice crystals, or a
combination of the two, including supercooled droplets (i.e.,
liquid droplets whose temperatures are below freezing).
 The two main type of mid-level clouds are altostratus and
altocumulus.
Low-level Clouds
 Low-level clouds are not given a prefix, although their
names are derived from "strato-" or "cumulo-,”
depending on their characteristics.
 Low clouds occur below 6500 feet, and normally
consist of liquid water droplets or even supercooled
droplets, except during cold winter storms when ice
crystals (and snow) comprise much of the clouds.
 The two main types of low clouds include stratus,
which develop horizontally, and cumulus, which
develop vertically.
Reflection and Refraction

Reflection is the returning, or bouncing' of a wave off of a surface which resists that kind
of wave.

Refraction is the change in direction of a wave when it passes into a new substance.

Both reflection and refraction involve a change in the direction of waves as they pass from
one medium to another. The amount of diffraction increases with increasing wavelength.

Most color that we can see is visible because our eyes perceive how objects absorb or
reflect certain wavelengths of light.

The white colors of clouds come from the condensed water vapor having a high reflective
quality. When all wavelengths of light are reflected back you see white. White clouds are
white if you notice, on sunny days. This is because you can see the sunlight directly
hitting them and see that light almost completely reflected back.

On cloudy days most sunlight is blocked by the translucent and refractive quality of cloud
cover. This makes clouds appear darker in color as part of the light has been uniformly
absorbed. The grey color comes from seeing clouds from beneath.

Some clouds are white, some are grey, and in special circumstances such as major
storms, clouds can have weird colors like green or red.
Cirrus Clouds
•
Thin, wispy clouds blown by high winds into long streamers.
 They are considered "high clouds" forming above 20,000 feet.
 Cirrus clouds usually move across the sky from west to east.
 They generally mean fair to pleasant weather.
Cirrocumulus Clouds
 Appear as small, rounded white puffs.
 The small ripples in the cirrocumulus sometimes
resemble the scales of a fish.
 A sky with cirrocumulus clouds is sometimes referred to
as a "mackerel sky."
Stratus Clouds
 Are uniform grayish clouds that often cover the entire
sky.
 They resemble fog that does not reach the ground.
 Usually no precipitation falls from stratus clouds, but
sometimes they may drizzle.
 When a thick fog "lifts," the resulting clouds are low
stratus.
Cirrostratus Clouds
 Thin, sheetlike high clouds that often cover the entire
sky.
 They are so thin that the sun and moon can be seen
through them.
Altostratus Clouds
•
Gray or blue-gray middle level clouds composed of ice crystals and water
droplets.
•
These clouds usually cover the entire sky.
•
In the thinner areas of the cloud, the sun may be dimly visible as a round
disk.
•
Altostratus clouds often form ahead of storms that will produce continuous
precipitation.
Nimbostratus Clouds
 Form a dark gray, "wet" looking cloudy layer associated
with continuously falling rain or snow.
 They often produce precipitation that is usually light to
moderate.
Cumulus Clouds

Puffy clouds that sometimes look like pieces of floating cotton.

The base of each cloud is often flat and may be only 3300 feet above the ground.

The top of the cloud has rounded towers.

When the top of the cumulus resembles the head of a cauliflower, it is called
cumulus congestus or towering cumulus.

These clouds grow upward, and they can develop into a giant cumulonimbus,
which is a thunderstorm cloud.
Altocumulus Clouds
 Middle level clouds that are made of water droplets and appear as
gray, puffy masses.
 They are sometimes rolled out in parallel waves or bands.
 The appearance of these clouds on a warm, humid summer
morning often means thunderstorms may occur by late afternoon.
Cumulonimbus Clouds

Thunderstorm clouds that form if cumulus congestus clouds continue to grow
vertically.

Their dark bases may be no more than 1000 feet above the Earth's surface.

Their tops may extend upward to over 39,000 feet.

Tremendous amounts of energy are released by the condensation of water vapor
within a cumulonimbus.

Lightning, thunder, and even violent tornadoes are associated with the
cumulonimbus.
References

http://eo.ucar.edu/webweather/images/403.gif
http://eo.ucar.edu/webweather/cumulus.html

http://eo.ucar.edu/webweather/cirrus.html
http://eo.ucar.edu/webweather/images/407.gif

http://eo.ucar.edu/webweather/images/450.gif
http://eo.ucar.edu/webweather/images/nimbus3.jpg

http://eo.ucar.edu/webweather/images/405.gif
http://eo.ucar.edu/webweather/images/nimbus2.jpg

http://eo.ucar.edu/webweather/images/cirruscum.gif http://eo.ucar.edu/webweather/cloud2.html

http://eo.ucar.edu/webweather/images/makeral.gif
http://www.universetoday.com/73198/what-are-clouds-made-of/

http://eo.ucar.edu/webweather/images/stratus2.jpg
http://www.ask.com/question/what-is-reflection-and-refraction

http://eo.ucar.edu/webweather/stratus.html
•
http://eo.ucar.edu/webweather/images/cumulus.gif
http://eo.ucar.edu/webweather/images/altostratus3.gif

http://eo.ucar.edu/webweather/images/stratus.jpg
http://eo.ucar.edu/webweather/images/428.gif

http://eo.ucar.edu/webweather/images/nimbostratus.jpg
http://eo.ucar.edu/webweather/images/altostratus2.gif

http://eo.ucar.edu/webweather/images/nimbostratus2.jpg
http://eo.ucar.edu/webweather/images/400.gif
http://ed101.bu.edu/StudentDoc/Archives/ED101fa06/angelad/clouds.html
References Continued
 http://www.crh.noaa.gov/lmk/?n=cloud_classification