Download The Relationship Between Air Pressure and Weather

Relationship to
Elementary Classroom
Standards – 4th grade
Nature of Science (2010)
Make predictions and formulate testable questions.
Design a fair test.
Plan and carry out investigations—often over a period
of several lessons—as a class, in small groups or
independently.
Perform investigations using appropriate tools and
technologies that will extend the senses.
Use measurement skills and apply appropriate units
when collecting data.
Test predictions with multiple trials.
Relationship to
Elementary Classroom
Standards (cont.) – 4th grade
Nature of Science
Keep accurate records in a notebook during
investigations and communicate findings to others
using graphs, charts, maps and models through oral
and written reports.
Identify simple patterns in data and propose
explanations to account for the patterns.
Compare the results of an investigation with the
prediction.
What is Air Pressure?
Force applied on a given object by the weight of
tiny particles of air also known as air molecules.
High Air Pressure Vs. Low Air Pressure
The amount of “empty” space between air
molecules determines whether the air pressure
is high or low.
If particles are more compressed and there is
less empty space, then the air pressure is high.
If particles have more “empty” space between
them, then particles have more freedom to
move, which results in low air pressure.
Barometers
Function = measure changes in air pressure
Types
Aneroid barometers
Fluid barometers
Mercury
Homemade
Balloon
Water bottle
Consultant: Steve Smith
K-12 Outreach Coordinator for Purdue
Department of Earth, Atmospheric, and
Planetary Sciences
Provides materials and activities to teachers in
surrounding schools
Provided us with our materials and suggestions
for barometers
Balloon Barometer
Change in pressure measured by movement of
toothpick
Toothpick above zero line = increased pressure
Toothpick below zero line = decreased pressure
Limits
Qualitative data
Relative to air pressure at which barometer was 1st
zeroed
Affected by temperature changes
Water Bottle Barometer
Changes in pressure measured by change in level of water
in bottle
Water level in bottle above zero line = increased pressure
Water level in bottle below zero line = decreased pressure
Limits
Very dependent on proper water levels and materials
Qualitative data
Relative to air pressure at which barometer was 1st zeroed
Consultant: Nick Barber
He is a graduate from Purdue with a Bachelor’s
in Meteorology.
Started the Purdue Weather Facebook page and
passed on the responsibility when he graduated.
Now holds an administrative position at the
CoRec
How does air pressure
affect weather?
Weather affects air pressure by increasing or
decreasing it depending on what sort of weather is
occurring at the time
You can have pressure drops in association with a
cold front (which is usually accompanied by rain
and thunderstorms, possibly severe if all the
ingredients are sufficiently present).
After the passage of weather systems, pressure
tends to increase, which brings about clearing.
This happens at the surface and with altitude.
Air Pressure and Weather
cont.
When air at the surface is heated by the sun, it
begins to rise via convection
This causes surface pressure to decrease and
pressure above to increase, which, if the air is
moist, will produce clouds, and potentially rain
and thunderstorms.
Air Pressure Around the
World
Air pressure is dependent upon altitude through a
pretty simple equation that relates the two indirectly
(i.e. as altitude increases, air pressure decreases
exponentially)
Pressure is also dependent upon temperature and air
density, which is usually averaged to one value, but
different regions can have different air densities,
thus providing you with differing pressures.
Around the World Cont.
One particular region of interest is central band
aka the Equatorial Low Pressure Zone, which is
more commonly referred to as the Inter-tropical
Convergence Zone (ITCZ).
Cont.
This is also seen on a smaller time scale with any
coast line where this differential heating zone
sets up, which causes what are called 'sea or
lake breezes', depending upon the body of
water.
Things to Keep in Mind
Air is warmed near a warm surface. So, the air
closest to the earth will be warmed the most.
As air rises, temps begin to drop
The number of air particles decrease as the
altitude increases
As air rises the pressure from the air above
decreases.
How Air Pressure Relates to
Weather
Weather is based on high air pressure and low air
pressure.
Low air pressure = cloudy and rainy weather
This happens because the air is rising and condenses
into clouds and rain.
High air pressure = sunny and dry weather
This happens because the air stays low and it tends to
stay dry as the air sinks.