Light Matters Activity

This simulation has students look at the interaction of sunlight and infrared on the Earth’s surface as well as carbon dioxide molecules in the atmosphere.

Activity developed by Tracy Ziettlow, UCAR AirWaterGas Teacher in Residence, with the support of science advisors Shannon Capps, Geoff Tyndall, and John Orlando.

Interactive simulation developed by the Concord Consortium.

Grade level: 9-12

Time Required: One class period for lab.

Learning Goal
Students will learn that carbon dioxide absorbs and re-emits infrared and not sunlight.

Lesson Format
Computer simulation and worksheet


Next Generation Science Standards

HS-PS3-2 Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative positions of particles (objects).

PS3.B Conservation of Energy and Energy Transfer

PS4.B Electromagnetic Radition

ESS2.D Weather and Climate: The foundation for Earth’s global climate systems is the electromagnetic radiation from the sun, as well as its reflection, absorption, storage, and redistribution among the atmosphere, ocean, and land systems, and this energy’s re-radiation into space.



  1. Print worksheet(s).
  2. Computer lab or classroom computers needed

For use in a physics course, introduce this activity by explaining that students will use their knowledge of the electromagnetic spectrum to understanding global warming and heat transfer within our atmosphere. Remind students that different waves have unique abilities due to their frequency or wavelength. Have students provide examples of different waves and their abilities (for example, microwaves heat food, visible light waves have different colors, and we feel heat from the Sun).


  1. Have students go to the Concord Consortium interactive model.
  2. Read directions on how to use the model and let them explore model and/or demonstrate model on screen.
  3. Have students follow directions on the Light Matters Questions worksheet provided.

Background information
The atmosphere is a mixture of many different gases including nitrogen (78%), oxygen (21%), and small amounts of argon, carbon dioxide (CO2), and other gases. The atmosphere also includes water vapor and small particles called aerosols. Carbon dioxide and other greenhouse gases are only present in small amounts, but they are able to have a big impact on the amount of heat trapped in the Earth system. Without carbon dioxide and other greenhouse gases, our planet would be inhospitably cold. However, a gradual increase in CO2 concentrations in Earth’s atmosphere is causing heat to be trapped and global climate to change. Greenhouse gases like carbon dioxide are able to trap heat energy but not incoming sunlight.

Sunlight is a part of the electromagnetic spectrum. There are also parts of the electromagnetic spectrum that are less familiar to many of us. Some have more energy and some have less. From highest to lowest energy levels, these sources from the Sun include gamma rays, x-rays, ultraviolet rays, visible light, infrared rays, and radio waves. Microwaves are a subset of radio waves.

The CO2 depicted in this model gives the impression that this interaction can take place at any level of the troposphere. CO2 resides throughout the troposphere (portion of the atmosphere closest to Earth), however, the reemission of infrared energy from CO2 molecules to the thinner parts of the atmosphere above finally occurs at a lower temperature. This lower temperature is experienced high in the Earth’s atmosphere, rather than at the surface of the Earth. This difference is important because the heat trapping, greenhouse effect occurs primarily because less heat is released to space from molecules that are at lower temperatures than would occur at higher temperatures like the molecules closer to the surface.

Most answers on the worksheet are constructed response and would be a great tool to assess understanding of the simulation and greenhouse gas behavior.

Extensions and Adaptations
As an advanced extension, have students investigate the vibrational modes for greenhouse gas molecules.

* An additional worksheet is provided to support special education and English language learners. The student can complete the worksheet while the simulation is run by the student, a Paraprofessional, or a partner student.
For more information

About the Atmosphere:

Carbon dioxide:

Waves of Energy Activity: