12
Changing air pressure causes the weather to change.
Warm air is lighter than cold air, so it rises.
When warm air rises, it leaves behind
an area of low pressure.
As air rises, it becomes
cooler and starts to sink.
This makes an area
of high pressure.
Standards Link: Physical Science: Students know
that states of matter depend on molecular motion.
Air is made of molecules.
When molecules heat up, they
move faster and farther away from
each other. This causes warm air to
be lighter than cold air, so it rises.
This is why hot air balloons float up
into the sky. Heaters blow hot air
into the balloon and it fills and rises.
When balloonists want to land, they
turn off the heat and float downward.
The tool scientists use to measure air pressure is
called a barometer. You can make one with
things found around your house. Here's how:
You can
measure
high
and low
pressure!
Cut off
the neck
of the
balloon.
Stretch the
balloon over
the top of the
jar. Secure it
with a string.
Glue the
end of the straw
onto the center
of the balloon.
Tape the scale on a
wall behind the jar so
that when the straw is
straight, it rests
halfway
between the
high pressure
and low
pressure marks.
Cut out
the pressure
scale below.
Over the next
few days,
watch the
straw move up
and down as
the air pressure
changes.
High pressure
usually brings
fair weather.
Low pressure often
brings cloudy,
unsettled weather.
You can
use your
barometer
and this chart
to see if this is
true!
1 balloon
1 drinking straw
1 wide-necked
glass jar
glue
scissors
string
Where is the straw
on the air pressure
scale (barometer)?
Actual
weather
outside
Date
Standards Link: Investigation:
Students know how to make a
systematic observation.
Standards
Link:
Investigation:
Conduct
simple
investigations.
Official Kids Mag www.kidscoop.comVicki Whiting January 2021
