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Temperature of the Masses
Observing how different air masses interact
Lily Frost
Overview: In a plastic shoe box, students will put 1 L of warm water that is colored red, and on
the other side they will put 1 L of cold water that is colored blue. These will be separated by a
cardboard divider. Then, they will remove the divider, and observe how the waters interact.
Background:
The weather is influenced greatly by air
and the way air moves. Think about
weather forecasts that are read in the
newspaper or heard on the television.
Often they talk about masses of air
coming from a region or area that is
bringing a certain temperature there. This
is due to certain air masses (Konvicka
1999). The different types of air masses
include Maritime Tropical, Maritime
Polar, Continental Tropical, and
Continental Polar. The way air masses
move is important too. The way they
move can create different fronts including
cold, warm, stationary, and occluded
fronts (Wiz Weather). An affect that can
happen due to fronts becoming distorted
are cyclones and anticyclones. Each of
these concepts is important to the way we
view the weather and how the weather is
affected by them. These concepts will be
further reviewed throughout this research
paper and will be demonstrated during the
in-class activity (Padilla 2005).
The cooperative activity will
involve learning about what happens
when cold air masses and warm air
masses meet. Through this students will
learn characteristics of air masses. Each
lab group will have a plastic shoe box
with a cardboard divider in the center,
dividing the box in half. One side of the
box will contain a liter of warm water
with red food coloring in it while the
other half will contain a liter of cold
water with 100mL of table salt and blue
food coloring. When the divider is
removed the two mixes will not mix but
they will form layers. This represents that
the cold air mass will move underneath
the warm air mass and the warm air mass
will rise (Padilla 2005). This represents
how the air moves and also how fronts
are related to air masses.
The first concept to cover will be
air masses, which relates to the activity.
An air mass is defined as a large body of
air that has similar humidity, temperature,
and air pressure at any given height. The
types of air masses that are found in
North America are maritime tropical,
continental tropical, maritime polar, and
continental polar. The characteristics of
an air mass rely on the moisture content
and temperature of the area where the
mass forms. Cold air is denser than warm
air and has a higher pressure. Warm air is
less dense and has a lower pressure.
Because of this, we can predict what will
happen in our activity (Padilla 2005).
Tropical air masses form in the
tropics and have low air pressure. Polar
air masses form close to north of 50
degrees north latitude and south of 50
degrees south latitude. These air masses
have high air pressure. Maritime air
masses form over oceans. The air
becomes very humid there because water
evaporates from the oceans. Continental
air masses form over land and have less
exposure to the moisture from bodies of
water (Padilla 2005). These air masses are
usually associated with the heat in late
spring through early autumn (Konvicka
1999).
Maritime Tropical air masses are
classified as warm and humid air masses
that form mainly over tropical oceans. In
the summer time, these air masses
typically bring humid and hot weather to
the areas. In the winter seasons a humid
air mass can bring heavy rain or snow to
the area. A maritime polar air mass is
described as a cold and humid air mass
that forms over the icy cold regions such
as: (see next page)
Age/Grade
level:
Fourth and Fifth (ages 911)
Skills:
Inferring- the students
will use what they
observe from the activity
to formulate
explanations about air
masses
Predicting- the
development of a
hypothesis prior to the
experiment
Formulating HypothesisBefore the activity,
students will describe
their “educated guesses”
to their lab mates
Experimenting- students
will learn to carefully
follow the directions of
the experiment so that
the results are
unanimous across the
board
Understand cause and
effect relationshipsstudents will discuss
what causes the water to
form separate layers
Objectives:
At the completion of this
activity a student will be
able to understand how
warm and cold air
masses interact with one
another, and how this
affects weather patterns.
Materials:
Cardboard divider
Plastic shoe box
Two drops of red food
coloring
Two drops of blue food
coloring
1 L of warm water
1 L of cold water
100 mL of table salt
Time
considerations:
Preparation Time: 3
minutes for pre- teaching
examples, asking pre
questions, and
developing a hypothesis.
2 minutes for each lab
group to set up..
Completion Time: 4
minutes for students to
complete activity. 2
minutes for post
questions, application,
and assessment
References:
Konvicka, T.
(1999). Teacher's
weather sourcebook.
Retrieved from Teacher
Ideas Press, EBSCO.
Englewood:Prentice
Hall. Retrieved from
http://web.a.ebscohost.c
om/ehost/detail/detail?vi
d=3&sid=ebc0b1ed048d-4e48-8422cf7435869f5b%40sessio
nmgr4003&hid=4209&b
data=JnNpdGU9ZWhvc
3QtbGl2ZQ%3d%3d#db
=nlebk&AN=21819
Padilla, M. J.,
Cyr, M., & Miaoulis, I.
(2005). Prentice Hall
Science Explorer.
Needham, MA: Prentice
Hall.
Weather Wiz
Kids weather
information for kids.
(n.d.). Weather Wiz
Kids weather
information for kids.
Retrieved October 2,
2014, from
http://www.weatherwizk
ids.com/weatherforecasting.htm
the North Pacific and North Atlantic
oceans. These masses bring fog, rain, and
cool temperatures to the West Coast
(Padilla 2005). These are often described
as “unstable” air masses (Weather Wiz).
A continental tropical air mass is a hot,
dry air mass that comes normally in the
summer over dry areas of the Southwest
and northern Mexico. These cover
smaller region than most other air masses
(Padilla 2005).
Last but not least, the continental polar air
masses form over northern and central
Alaska and Canada. The ones that form
close to the Arctic Circle are known to
bring very cold weather with very low
humidity. In the winter time these masses
bring clear, dry, and cold air to many
places in North America. In summer time,
though, the air mass is slightly milder
(Padilla 2005). The air is usually cool and
average, opposed to the winter (Konvicka
1999).
A front is defined as the
boundary where the air masses meet
(Padilla 2005). There are four types of
fronts which include cold, warm,
stationary, and occluded. Cold fronts are
boundaries between two air masses with
one warm and one cold. In this front, the
cold air mass would move so that the cold
air replaces the warm air. A warm air
front replaces and overtakes the colder air
mass. You can often tell when a warm
front is coming because of the cloud
shapes and how the changing of the
clouds result in precipitation and fog. A
thunderstorm can be a result of a warm
front (Konvicka 1999). A stationary front
is a boundary between two air masses that
does not move. However, some stationary
fronts move side to side for several
hundred miles a day. Lastly, an occluded
front is a combination of two fronts that
form when a cold front moves so that it
meets with a warm front and then
overtakes it (Wiz Weather).
When an air mass collides to
form a front, the boundary between those
fronts sometimes becomes distorted. This
distortion is caused by surface features
including mountains or strong winds.
When they come in contact with these
features, bends develop along the front
and the air begins to swirl. These swirls
cause a low pressure center. When a low
pressure area is formed it creates a
cyclone. In a cyclone the winds spiral
toward the center of the system. As air
rises in a cyclone, the air cools, which
forms precipitation and clouds. This is
why cyclones are important in the United
States (Padilla 2005).
An anticyclone is the opposite of
a cyclone. It is defined as high pressure
centers of dry air. The winds spiral
outward from the center of the
anticyclone, which move toward the areas
of lower pressure. As the cold air falls, it
warms up, so its relative humidity drops.
This descending air causes dry, clear
weather (Padilla 2005).
It’s important to always pre-teach a
lesson before the activity, and to build
background knowledge. The teacher
should ask which is denser, warm air or
cold air, and what students think will
happen if a large mass of cold air came
into contact with a large mass of warm
air? The answer is cold air, and that the
cold air will move below the warm air,
causing the warm air to rise. Remind the
students that this is similar to the common
fact that “hot air rises.” The teacher
should also tell students that large masses
of cold and warm air often meet in the
atmosphere and that the meeting of these
masses with different temperatures causes
most of the weather people get in the
United States (Padilla 2005).
Key concepts and ideas that are important
to remember during this lesson are how to
classify air masses and what questions to
ask. It may be simplest for the teacher to
explain that the word “mass” refers to a
quantity of air of considerable size. The
mass of an object is a measure of the
amount of matter, or what is inside, the
object. The teacher can also reflect and
compare these concepts to the area you
live in. He or she should ask students,
based on what they have learned, to
identify which air masses affect the
weather and weather patterns around the
area they live and what effect they may
have on the weather too (Padilla 2005).
Preparation:
To prepare for this activity, the teacher
must make she he/she knows how the
different temperatures of water relate to
the air masses. They should gather all
materials and set up in the classroom, to
make sure they are not wasting time with
the students.
Materials (again)
Cardboard divider
Plastic shoe box
Two drops of red food coloring
Assessment:
The teacher will know the students
completed the objectives when they know
how this activity relates to air masses in
the atmosphere.
Q:What happens when a warm air mass
meets a cold air mass?
Q:What has this activity proved/shown
us?
Q: Which is denser, a cold air mass or a
warm air mass?
Two drops of blue food
coloring
1 L of cold water
100 mL of table salt
Pre-questions:
Which is denser, warm
air or cold air? A: cold
air
What do you think
would happen if a large
mass of cold air came
into contact with a large
mass of warm air? A:
the cold air would move
below the warm air,
causing the warm air to
rise.
Procedure:
1.
2.
3.
4.
Place a
cardboard
divider across
the middle of a
plastic shoe box
Add a few
drops of red
food coloring to
a liter of warm
water. Pour this
liquid
(representing
low density
warm air) into
the shoe box on
one side of the
divider
Add about 100
mL of table salt
and a few drops
of blue food
coloring to a
liter of cold
water. Pour the
blue liquid
(representing
high-density
old air) into the
shoe box on the
other side of the
divider
Quickly remove
the divider,
making sure to
watch both sides of the box
carefully
What is happening to the different
colored waters? (Did they mix? Which
one is on top?)