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Investigation 2 – PreLab









Climate change analysts use atmospheric data to create models and to make predictions about what will happen to Earth’s climate in the future, and what impacts, if any, these changes will have on natural ecosystems and civilizations. They evaluate both economic and physical impacts.


This Investigation is designed to help you to answer the following Focus Questions:

  • What types of air movements cause areas of high and low pressure? 
  • Why do differences in pressure cause wind? 
  • How are differences in pressure measured? 

Note: These questions are located in your SDR at the beginning and end of the Investigation.


As a class, read the Background(s) in the Investigation. When finished, discuss the following concepts as a class:

  • The molecules of gas that compose the atmosphere exerted a force on the surface of the Earth. Atmospheric pressure is a measure of that force per unit area.
  • Pressure is calculated as 

ATMOS 2 Pre Formula

  • Because atmospheric pressure is a type of pressure, the same equation can be used to determine atmospheric pressure.
  • Pressure is measured by meteorologists in the units of millibars (mb). The greater the millibars, the higher the pressure.
  • Anything that increases the downward force increases the pressure at that area of the Earth. Anything that decreases the downward force decreased the pressure at the area of the Earth.
  • A high-pressure area or high-pressure system has a pressure that is higher than any place next to it.
  • A low-pressure area means that the area has a pressure that is lower than any place next to it.
  • Meteorologists indicate areas of different pressure on a map. The areas that have the same pressure are connected by a line called an isobar.




The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.

  • atmospheric pressure
  • high-pressure system
  • low-pressure system
  • barometric pressure
  • barometer
  • pressure gradient force 
  • isobar
  • wind

Note: Definitions of these terms can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.


  • The focus of this CELL is to better understand the changes that can occur to the atmosphere and how these changes result in changes in the weather by examining temperature, pressure, and amount of precipitation received by different areas on Earth.
  • Recall what you have already learned about temperature and the movement of air from the experiments conduction in Investigation One.
  • Do you think the movement of air as a result of temperature differences can affect other areas of weather such as atmospheric pressure? 
  • The focus of Investigation Two will be an exploration of atmospheric pressure and air movement in the atmosphere. At the end of the investigation, you will have an opportunity to pull together the information from Investigations One and Two to answer this question.
  • Consider the following questions. You will likely formulate answers to these questions after you have completed the Investigation.
    • What is pressure?
    • What is meant by high pressure and low pressure?
    • What is wind and what causes wind?
    • What does pressure have to do with the weather?
  • Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful in the lab.
  • After the video, divide into lab groups to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.


You should review the Investigation and the video in preparation for the Lab.