Mini Lesson/Activity

Energy and Matter: Longwave Radiation (Student Activity)

Mini Lesson

Review the video and text below and answer the questions that follow.

Credit: NASA Scientific Visualization Studio

Suomi NPP CERES Longwave Flux at Top-Of_Atmosphere colorbar


  1. What is longwave radiation?
  2. What time period does this video show longwave radiation on Earth?
  3. What colors represent areas where the most energy is being emitted out to space?   Least energy?
  4. What are the units of these measurements?
  5. Where do you expect to find the warmest temperatures?  Coldest?
  6. What drives Earth's climate engine?
  7. What system of the Earth system is constantly adjusting to maintain balance between the energy that reaches the Earth from the Sun and the energy that flows from the Earth back out to space?
  8. What parts of the aforementioned system reflects energy back to space?

This video shows a global view of the top-of-atmosphere (TOA) longwave radiation from January 26 and 27, 2012. Heat energy radiated from Earth (in Watts per square meter) is shown in shades of yellow, red, blue and white. The brightest-yellow areas are emitting the most energy out to space, while the dark blue and bright white areas (clouds) are much colder, emitting the least energy. Increasing temperature, decreasing water vapor, and decreasing clouds all tend to increase the ability of Earth to shed heat out to space.

The Sun's radiant energy is the fuel that drives Earth's climate engine. The Earth-atmosphere system constantly adjusts to maintain a balance between the energy that reaches the Earth from the Sun and the energy that flows from Earth back out to space. Energy received from the Sun is mostly in the visible (or shortwave) part of the electromagnetic spectrum, where Earth's atmosphere is transparent. About 30% of the solar energy that comes to Earth is reflected back to space by clouds and aerosols or bright surfaces. The ratio of reflected-to-incoming energy is called "albedo" from the Latin word meaning whiteness. The solar radiation absorbed by the Earth causes the planet to heat up until it is radiating (or emitting) as much energy back into space as it absorbs from the Sun. The Earth's thermal emitted radiation is mostly in the infrared (or longwave) part of the spectrum, where Earth's atmosphere is not transparent. Thus, much of the emission to space is from the higher levels of the atmosphere. The balance between incoming and outgoing energy is called the Earth's radiation budget.

For more information on CERES see

Teacher Note

Teachers, these mini lessons/student activities are perfect "warm up" tasks that can be used as a hook, bellringer, exit slip, etc.

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