The Earth absorbs a portion of this radiation, but _________________ wavelength radiation is reflected back into the atmosphere

The correct answer is longer.

Explanation: The Earth absorbs solar radiation in the shorter wavelengths (such as ultraviolet and visible light) and re-emits energy in the form of longer wavelength radiation, primarily infrared. Some of this longer wavelength radiation is then reflected back into the atmosphere. This process is important for maintaining the Earth’s temperature.