Nicole Harris
December 6, 2003
Portfolio Component #3 - Personal Growth
Misconceptions of Clouds and the Atmosphere
The reason I chose the topic of clouds, along with the
topic of the atmosphere, is because I learned that clouds form due to
the state of the atmosphere at that time. But, before, I learned
to put the two together, in my mind, the two had no connections to each
other. The atmosphere to me was just the air around me, no more
and no less. The atmosphere will be cold at certain times and
warm at other times. I thought the atmosphere only consist of
oxygen. I thought that clouds were simply something that "mother
nature" created but only on rainy and not so sunny days. I did
think that clouds were the reason for it raining but I also thought
clouds existed after it rained and on muggy and foggy days. I
don't think my misconceptions were from the lack of teachings in
elementary, middle, and high school, but rather from my lack of
interest in science and me wanting to come to my own conclusions about
what the atmosphere is and how and why clouds are really formed.
Identification of Science Standards
According to the Michigan Curriculum Framework Science Content
Benchmarks, the topic of clouds and the atmosphere that I am now
familiar with is deemed appropriate for elementary and middle school
aged students. Michigan students will learn about
this topic in both elementary and middle school under Strand V. Using Scientific Knowledge in
Earth Science : Standard V.2 - The Hydrosphere and Standard V.3 - The
Atmosphere and Weather. Under the hydrosphere standard,
"all elementary students will describe the characteristics of water and
demonstrate where water is found on earth" (Michigan Curriculum
Framework, p.116). Under the atmosphere and water standard, "all
elementary and middle school students will investigate and describe
what makes up weather and how it changes" and at the middle school
level, "all students will explain what causes different weather"
(Michigan Curriculum Framework, p. 118-119). The detailed
standards below will show how students will meet and succeed in the
scientific learning process at both elementary and middle school
levels:
Elementary School
1. Describe how water exists on Earth in
three states. This standard is important in discussing my
topic because all three states of water exist in the atmosphere and in
the process of cloud formation.
2. Describe weather
conditions. This standard is important because students
will learn of certain forms of precipitation that exist in the
atmosphere and on Earth when clouds are present.
Middle School
1. Explain patterns of changing weather and
how they are measured. This standard is important because
middle -school aged students will learn that sudden temperature and
cloud changes will have an effect on the weather. Students will
also know how the water vapor in the atmosphere is imporatnt to weather
and clouds.
2. Describe the
composition and characteristics of the atmosphere. This
standard is important because most clouds form on the basis of the
atmosphere. Before students understand the process of cloud
formation, they must understand what the atmosphere is composed of and
what makes up the atmosphere.
3. Explain the behavior
of water in the atmosphere. This standard shows how
students will learn the water cycle process and understand it's
importance in the atmosphere and how clouds are formed and give-off
precipitation.
College Level Description of Clouds and the
Atmosphere
The three changes of state that water undergoes are so
important when talking about the atmosphere and cloud formation.
The three changes of state are solid, liquid, and gas. According
to Figure 16.2 in Earth Science, "water can change from one state of
matter to another at the temperatures and pressures experienced on
Earth" (Tarbuck and Lutgens, p. 434). When a solid changes into a
liquid, this process is called melting. During this state of
change, the atmosphere loses energy (or, heat) and the water gains
energy (or, heat). When a liquid turns into a gas, it is called
evaporation. At this state the atmosphere loses heat and the
water gains heat. The opposite change of state of evaporation is
condensation. This state occurs when the gas turns into a liquid
and the atmosphere gains energy. When a solid changes into a gas,
this process is called sublimation. To change a gas back into a
solid is called deposition.
The most important change of state in the atmosphere is gas. In
the atmosphere, this gas is called water vapor. According to the
textbook, "water vapor is an odorless, colorless gas that mixes with
the other gases of the atmosphere" (Tarbuck and Lutgens, p.434).
Within, the water cycle, evaporation (or water vapor) is carried into
the atmosphere by large bodies of water such as oceans. When
condensation changes into a liquid state, clouds are produced.
Again, this is an important part of the water cycle that generates
clouds. Clouds, in turn, give of various forms of precipitation
such as rain, snow, and sleet. The water cycle is very dynamic in
which it transports the three states of water in our atmosphere and on
Earth's surface.
As mentioned earlier, water vapor mixes in with two other important
gases that "make up 99 percent of the volume of clean, dry air"
(Tarbuck and Lutgens, p.407). These two gases are nitrogen and
oxygen. "Although these gases are the most plentiful components
of air and are of great significance of life on Earth, they are of
minor importance in affecting weather phenomena" (Tarbuck and Lutgens,
p. 407). But, the textbook does state that carbon dioxide is
effective in absorbing heat and therefore, "influences the heating of
the atmosphere." Another component of the atmosphere is water
vapor. The textbook states that water vapor is like carbon
dioxide in which it has a role in heating up the atmosphere.
Water vapor is also found in clouds. Another important component
of the atmosphere is dust particles. These particles come from
many sources and can be in the form of a solid or a liquid. Dust
particles are important to cloud formation also. Dust particles
act as something for water vapor to grab hold to and condense.
"Scientist agree that water vapor is the most important gas in the
atmospheric processes" (Tarbuck and Lutgens, p. 436). The
textbook refers to the term humidity when speaking of the amounts of
water vapor in the atmosphere. When the atmosphere has reached
its capacity in the amount of water vapor, the gases began to turn into
a liquid. This is what scientist call saturated air. When
the air is highly saturated, it is said to have reached 100% relative
humidity or sometimes even greater than 100%. The textbook does
mention that saturation is very temperature dependent. This means
that for every 10º C increase in temperature, the amount of water
vapor needed for saturation doubles. This brings me to the topic
of clouds in more detail. "When the air aloft is cooled below its
saturation level, some of the water vapor condenses to form
clouds. As clouds are made of liquid droplets, this moisture is
no longer part of the water vapor content of the atmosphere" (Tarbuck
and Lutgens, p. 438).
I learned that three things need to occur in order for a cloud to form:
1) temperature differences, 2) condensation nuclei, and 3) water
vapor. When there is a mixture of hot air and cold air clouds
form. The textbook discusses adiabatic temperature changes which
means that when the air is cooled or warmed, it expands or
compresses. This temperature does not gain or lose energy.
Condensation nuclei is another process that needs to occur for clouds
to form. These dust particles are also in the atmosphere.
Condensation nuclei is the same as dust particles and act as something
for the water vapor to grab hold to. On hot summer days, you will
see this water vapor turn into liquid on the outside of a cold beverage
that you are drinking. The textbook refers to condensation nuclei
as "tiny bits of particulate matter" that "serve as surfaces for water
vapor condensation" (Tarbuck and Lutgens, p. 449). The textbook
does stress how important these nuclei are to the production of
clouds. Water vapor again is important to cloud formation.
Water vapor is "invisible to the eye", but is all around us or the
atmosphere. Because water vapor is a gas and forms clouds which
is liquid water, a change of state is occurring. As mentioned
earlier, when water goes from a gas state to a liquid state,
condensation has occurred. This is an important connection
because it proves how water vapor and condensation nuclei play an
important role together in cloud formation, along with temperature
differences. The textbook discusses four mechanisms that cause
air to rise in relation to temperature changes. Orographic
lifting occurs when "air is forced to rise over a mountainous
barrier." Frontal wedging occurs when "warmer, less dense air, is
forced over cooler, denser air." Convergence is "a pileup of
horizontal air flow resulting in upward movement." Localized
convective lifting occurs when "unequal surface heating causes
localized pockets of air to rise because of their buoyancy." (The
textbook has greats diagrams of each mechanism on page 463.)
We did a worksheet in class that helped us determine what factors
determine the base and the height of a cloud. The base is the
bottom of the cloud and the relative humidity determines the
base. When the relative humidity is decreased, this means less
water vapor, and less water vapor means less clouds which makes the
cloud's base higher. If the relative humidity is too low, the
cloud won't form. When given a certain relative humidity, the
cloud grows in height and slightly in width as the ground level
temperature rises. The conditions that determine the height of a
cloud is the temperature of the air at the top of the cloud, as long as
the cloud and the air are the same temperature. This means that
they have the same density and the same temperature and, therefore, has
no more of a reason for the cloud to rise meaning the cloud has reached
its height. The conditions that lead to thick clouds are very
high temperatures and high relative humidity. The temperature on
the inside of the cloud is said to be warmer than the temperature on
the outside of the cloud because when water goes from a gas to a liquid
it loses heat. Condensation of water vapor into liquid droplets
allow the release of heat energy in the cloud. This all goes back
to the three changes of state mentioned earlier. "Clouds are
classified on the basis of their form and height" and the three basic
forms are cirrus, cumulus and stratus. The textbook discusses
several types of high, middle and low clouds. The high clouds are
cirrus, cirrostratus, and cirrocumulus. The middle clouds are
altocumulus and altostratus. The low clouds are stratus,
stratocumulus and nimbostratus. From these various clouds fall
many forms of precipitation. The textbook names nine types of
precipitation: mist, drizzle, rain, sleet, glaze , rime, snow, hail,
and grumpel.
Reflection
There is so much more information to give and learn about
the atmosphere and clouds. I was interested in doing my final
project on this topic because of my recent airplane ride. I was
looking out the window at one point and could see the cities below but
once the airplane reached a certain altitude, I wasn't able to see
anything. I guess this was due to clouds in the sky. Or,
maybe you just reach a certain point in the atmosphere were the land is
no longer visible. I was just so fascinated by what I learned and
so many questions popped into my mind about the atmosphere and the
clouds. A great portion of my knowledge came from the
instructor. The instructor gave me so many resources to turn to
so that I would have a clear understanding of the topic. By
attending class regularly, I was able to engage in experiments that
aided in my learning as well as work in groups. The instructor
used excellent diagrams to help me understand these processes.
Some were picture diagrams, tables, web charts, and the very
informative Target, Factor, and Analog table. The textbook was
very useful. It explained a lot of the things covered in class
and was convenient for when I left class clueless on subjects that just
were not registering that day. Earth Science is a very wonderful
subject and I look forward to furthering my learning experience so I
can be an excellent Earth Science teacher.
Works Cited
Michigan Department of Education. Michigan Curriculum Framework Science
Benchmarks. Summer 2000. Michigan Curriculum Framework. September 24,
2004
www.michigan.gov/documents/MichiganCurriculumFramework_8172_7.pdf
Tarbuck, Edward J. and Frederick K. Lutgens. Earth Science. New Jersey :
Pearson Education, Inc., 2003.