Hands-on Activity: Barometric Pressure: Good News – We're on the Rise!

Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

A close-up photograph shows the face of a barometer instrument with an arrow hovering between the markings for Rain and Fair.
Students learn about barometric pressure and weather forecasting.
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Copyright © Microsoft Corporation, 1983-2001.

Summary

Students build and observe a simple aneroid barometer to learn about changes in barometric pressure and weather forecasting.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

Often, pollutants that damage the environment and affect public health are carried by the wind hundreds of miles from their origins. Engineers must understand barometric air pressure and analyze wind patterns to track the source of air pollution, and predict the future path and expected dispersion of traveling air pollution. Engineers use this information to monitor and reduce pollution levels and determine new pollution prevention programs.

Learning Objectives

After this activity, students should be able to:

  • Understand and explain how a barometer works.
  • Build a model aneroid barometer and use it to indicate when atmospheric pressure is rising or falling.
  • Graph the changes in barometric pressure during a two-week period.

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Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Collect data to provide evidence for how the motions and complex interactions of air masses results in changes in weather conditions. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Draw a scaled picture graph and a scaled bar graph to represent a data set with several categories. Solve one- and two-step "how many more" and "how many less" problems using information presented in scaled bar graphs. (Grade 3) Details... View more aligned curriculum... Do you agree with this alignment?
  • Display numerical data in plots on a number line, including dot plots, histograms, and box plots. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
  • Describe weather conditions based on data collected using a variety of weather tools (Grade 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • Use data collection tools and measuring devices to gather, organize, and analyze data such as temperature, air pressure, wind, and humidity in relation to daily weather conditions (Grade 5) Details... View more aligned curriculum... Do you agree with this alignment?
Suggest an alignment not listed above

Materials List

Each group needs:

  • 1 empty, wide-mouth jar
  • 1 sheet of Mylar or a helium-quality balloon (the same material used for aluminized party balloons; Mylar is relatively impermeable to gas)
  • 1 heavy, thick rubber band
  • 1 small ball of poster putty (or chewing gum or other adhesive)
  • 1 toothpick (or 6-inch piece of dry spaghetti noodle or broom straw)
  • 1 piece of cardboard, ~8 x 10 inches, for the barometer scale
  • The day's barometric pressure, from newspaper weather page, television or radio weather broadcast, or weather website
  • Barometric Pressure Log, one per student
  • (optional) graph paper (only needed if students are graphing data), one sheet per student

Introduction/Motivation

Weather forecasters make predictions on the basis of meteorological data such as wind speed, barometric pressure, relative humidity and temperature. Meteorologists know that one of the most valuable pieces of information in making predictions is atmospheric (barometric) pressure. In fact, the accuracy of a weather forecast based solely on pressure trends is about 70-75%. In this activity, students build an aneroid barometer. Although it is not as accurate as a water barometer, it is more convenient to make and use.

Meteorologists often use maps of air pressure to predict weather patterns. The maps generally have isobars (lines [contours] of equivalent air pressure, as seen in Figure 1). You may have seen maps like this on television or in the newspaper.

A map of North America with overlaid symbols such as dashed lines, Hs (high pressure), Ls (low pressure), snow, rain, and lines with triangles or bumps. The symbols indicate low-pressure zones in the midwestern U.S. and western Mexico, and a high pressure zone in central northern Canada.
Figure 1. A weather map shows North America with pressure isobars. Pressures range from 1,000 in the central U.S. to 1,020 in northern Canada.
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Copyright © NOAA http://www.hpc.ncep.noaa.gov/noaa/noaa.gif

High-pressure zones are usually accompanied by fair weather, while low-pressure zones are often associated with stormy weather. Pressure and temperature differentials cause winds. Air moves from regions of high pressure to regions of low pressure. For example, on-shore breezes occur on summer afternoons at the beach when warm air on the land rises and leaves a partial vacuum that is filled by cooler air off the water. Engineers study wind patterns to determine the source of air pollution. Often, pollutants that damage the environment and affect public health are carried by the wind hundreds of miles from their origins.

The most common method of measuring altitude uses the altimeter, which is a barometer that measures atmospheric pressure. As one goes up in altitude, the air pressure decreases.

You may remember from the Air Pressure Experiments: I Can't Take the Pressure! activity (Air Pressure unit, Lesson 4) that pressure is measured in various units. The units reported in the newspaper or on television are usually in inches of mercury. Sometimes atmospheric pressure is given in millibars (a metric equivalent). Below are some of the common units used to measure pressure and their equivalents at sea level:

  • 30.32 in Hg (inches of mercury)
  • 1,013 millibars
  • 1.013 x 105 Pa (Pascal or N/m2)
  • 1 atm (atmosphere)
  • 760 mm Hg (millimeters of mercury)
  • 14.7 lb/in2 (psi, pounds force per square inch; if 1-pound weight rests on 1-square inch of surface area, the pressure is 1 psi)

Procedure

Before the Activity

  • Gather materials and make copies of the Barometric Pressure Log.
  • Find a source for the daily barometric pressure such as the weather page from a local newspaper, a television/radio weather report, a local newspaper or TV news website or other website like weather.com.

With the Students

  1. Ask the students: What is a barometer? Have them brainstorm some ideas and write them on the board. Tell them they will learn more about barometers in today's activity.
  2. Divide the class into groups of four students each.
  3. Distribute the supplies to each group: 1 wide-mouth jar, 1 piece of Mylar, 1 rubber band, a small ball of poster putty, 1 toothpick, 1 piece of cardboard.
  4. Seal the jar with the Mylar by stretching the sheet until it forms a tight drum over the top. Use a rubber band to hold it in place. See Figure 2.
  5. Place a small piece of poster putty in the center of the membrane and place the toothpick in the putty, so that it is standing up, vertically. See Figure 2.
  6. As the atmospheric pressure decreases, the pressure inside the jar exceeds the external pressure and forces the membrane to bulge up and the toothpick to move down. Conversely, if the atmospheric pressure increases, the membrane bends inward and the needle (toothpick) swings up (see Figure 2).

Two photographs both show a glass jar with a rubber band securing a piece of Mylar tight across the jar mouth and a toothpick stuck vertically into a piece of putty on top of the Mylar lid. In the left photo, the toothpick points straight up. In the right photo, the toothpick leans a bit to the right.
Figure 2. Student-made barometers at high (left) and low (right) atmospheric pressure.
copyright
Copyright © 2003 Daria Kotys-Schwartz, Integrated Teaching and Learning Program, College of Engineering and Applied Science, University of Colorado Boulder

  1. Place the barometer near a wall and attach the cardboard to the wall behind it. To calibrate the barometer, write today's barometric pressure reading on the piece of cardboard at the spot where the needle is pointing. Repeat this procedure on days when the pressure is significantly different. Although your barometer may not be very accurate, you should be able to observe major changes in barometric pressure.
  2. Barometers keep track of air pressure. When air pressure is high (indicating fair weather), the toothpick points up because air is pressing down on the Mylar. When air pressure is low (indicating the bad weather is coming), the toothpick points down because air inside the jar is pushing up against the balloon.
  3. Pass out the Barometric Pressure Logs. Have students observe their barometers for 1-2 weeks, recording the direction the needle is pointing on their barometer and the actual barometric pressure for that day.
  4. On the logs, have students make predictions about the weather, reminding them that the accuracy of a weather forecast based solely on pressure trends is about 70-75%. Also, their forecast is valid for 12-24 hours into the future so they can make predictions for the next day.
  5. Have students record the actual weather conditions, too.
  6. At the end of the observation period, review the data to determine if there is a relationship between changes in barometric pressure, changes in the weather and being able to predict the weather. Review with students the summary questions on the Barometric Pressure Log. Ask the students: What is a barometer? (Answer: A device for measuring atmospheric pressure.)
  7. (optional) Have students make a graph of barometric pressure (on the y-axis) vs. time, in days (on the x-axis).

Attachments

Safety Issues

Make sure to place the barometers in a place in which they will not be knocked over or broken.

Troubleshooting Tips

This activity is especially suitable during the wet season because changes in pressure are more notable during the course of the day.

Try not to begin this activity on a day with an unusually high or low pressure, which could upset the barometer calibration.

When graphing the data, treat the days as Day 1, Day 2 through Day 14. If there are no data points for the weekend days, have students make predictions for the missing data, based on the graph.

Assessment

Pre-Activity Assessment

Brainstorming: As a class, have the students engage in open discussion. Remind students that in brainstorming, no idea or suggestion is "silly." All ideas should be respectfully heard. Encourage wild ideas and discourage criticism of ideas. Have them raise their hands to respond. Write answers on the board. Ask the students:

  • What is a barometer? (After the brainstorming session, tell them they will learn more about barometers in today's activity.)

Activity Embedded Assessment

Worksheet: Use the Barometric Pressure Log to help students follow along with the activity's 1-2 week data collection.

Post-Activity Assessment

Worksheet: After two weeks of observation, review the Barometric Pressure Logs and ask students:

  • Did your barometer predict any weather changes? Were the predictions correct?
  • Did it predict anything else?
  • Do you see any trends? Describe what you see.

Weatherman Explains: Ask students to write a paragraph to a local engineering company about their barometer and what it represents. Also, have the students explain to the engineering company why the engineers may need to know this information.

Activity Extensions

To build a water barometer, see pg. 62 in 175 Science Experiments to Amuse and Amaze Your Friends, by Brenda Walpole.

Invite a meteorologist into your classroom to speak about weather prediction.

Some newspapers list the barometric pressure at different times throughout the day. Have the students graph the pressure information over the course of a day. Plot other days on the same graph in different colors.

Activity Scaling

  • For younger students, build the barometer as a class, and take turns reading it.
  • For older students, in addition to building barometers and making weather predictions that they verify with actual measurements in later classes, incorporate a newspaper activity. Bring to class the weather pages from different newspapers. Before starting the activity, have each team read through their weather page and write a paragraph describing the nation's air pressure for their day, and how they would use that information to forecast the coming weather. Have each team complete their paragraphs before they receive their materials for the rest of the activity.

References

Cunningham, J. and Herr, N. Hands-On Physics Activities with Real-Life Applications. West Nyack, NY: The Center for Applied Research in Education, pg. 199, 1994.

Walpole, Brenda. 175 Science Experiments to Amuse and Amaze Your Friends. Random House, pg. 62, 1988.

Contributors

Amy Kolenbrander; Daria Kotys-Schwartz; Janet Yowell; Natalie Mach; Malinda Schaefer Zarske; Denise W. Carlson

Copyright

© 2004 by Regents of the University of Colorado

Supporting Program

Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

Acknowledgements

The contents of this digital library curriculum were developed under grants from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation (GK-12 grant no. 0338326). However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: February 8, 2018

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