Mini Lesson

Energy and Matter: Shortwave Radiation (2012)

Mini Lesson

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

This global view shows CERES top-of-atmosphere (TOA) shortwave radiation from January 26 and 27, 2012. Light energy reflected from Earth (in Watts per square meter) is shown in shades of blue and white. The brightest-white areas (generally clouds) are reflecting the most energy out to space, while the darker blues areas reflect much less. Increasing cloud cover and snow/ice cover all tend to increase the ability of Earth to reflect energy out to space.

Reflected shortwave flux at the top-of-atmosphere colorbar for Suomi NPP CERES
Reflected shortwave flux at the top-of- atmosphere color bar for Suomi NPP CERES

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 the Clouds and Earth's Radiant Energy System (CERES) see http://ceres.larc.nasa.gov.

Credit: NASA Scientific Visualization Studio

  1. What is shortwave 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. What drives Earth's climate engine?
  6. 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?
  7. What parts of the aforementioned system reflects energy back to space?

Teachers who are interested in receiving the answer key, please contact MND from your school email address at mynasadata@lists.nasa.gov.