Earth's surface and the clouds absorb visible and invisible radiation from the sun and re-emit much of the energy as <answer>infrared</answer> back to atmosphere. Certain substances in the atmosphere, chiefly cloud droplets and water vapor, but also carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, and chlorofluorocarbons, absorb this <answer>infrared</answer>, and re-radiate it in all directions including back to Earth. Thus, the greenhouse effect keeps the atmosphere and surface much warmer than if the <answer>infrared</answer> absorbers were absent from the atmosphere.
After Earth surface's absorbs radiation, in what spectrum is much of it re-emitted?
infrared