1. The Relationship Between Air Pressure and Weather
By: Laura Capps, Kylie Rife, Shannon Collyer and Lindsay Freebourn

2. 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.
Laura

3. 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.
Laura

4. What is Air Pressure?
Force applied on a given object by the weight of tiny particles of air also known as air molecules.
Kylie

5. 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.
Kylie

6. Barometers Function = measure changes in air pressure Types
Aneroid barometers
Fluid barometers
Mercury
Homemade
Balloon
Water bottle
Laura

7. 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
Laura

8. 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
Laura

9. 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
Laura

10. 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
Shannon

11. 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.
Shannon

12. 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.
Shannon

13. 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.
Shannon

14. 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).
Shannon

15. Shannon

16. 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.
Shannon

17. Shannon

18. 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.

19. 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.