Black Body Radiation

• What is blackbody radiation?

  Radiation emitted by a perfect black body
• How does the temperature of an object relate to radiation?

  It depends on absorbed and emitted radiation balance
• What surfaces are the best absorbers and emitters of infrared radiation?

  Matte black surfaces
• What happens to infrared radiation emitted by hotter objects?

  Hotter objects emit more infrared radiation
• How does the wavelength of radiation change with temperature?

  Hotter objects emit shorter wavelength radiation
• What does a perfect black body do with radiation?

  Absorbs all incident radiation without reflection
• What is the relationship between absorption and emission of radiation?

  Good absorbers are also good emitters
• What happens to an object warmer than its surroundings?

  It emits more radiation than it absorbs
• What happens to a cooler object in warmer surroundings?

  It absorbs more radiation than it emits
• What occurs when an object maintains a constant temperature?

  It absorbs and emits radiation at the same rate
• How does the Earth gain or lose energy?

  Through absorbing or emitting radiation
• What type of radiation does the Sun emit?

  Short wavelength radiation like visible light
• What happens to some of the Sun's radiation when it reaches Earth?

  Some is reflected by clouds
• What effect does absorbed radiation have on Earth's temperature?

  It causes the temperature to increase
• What type of radiation does the Earth emit back into space?

  Infrared radiation
• How do greenhouse gases affect Earth's emitted radiation?

  They trap some infrared radiation in the atmosphere
• What is the impact of human activity on greenhouse gases?

  It increases greenhouse gas levels in the atmosphere
• What is the effect of cloud cover on energy radiation from Earth?

  Cloudy nights are warmer than clear nights
• Why do clouds keep nights warmer?

  They reflect infrared radiation back to Earth