High resolution spectroscopy resolves individual rotational transitions in a vibrational band. Reflection spectra detect broad troughs are produced when solar photons pass through the atmosphere and are absorbed before being scattered back by clouds. Symmetrical molecules have quadrupole moments, but no dipole moments, so they exhibit only small absorption. Reflection spectra are taken in the visible to near infrared portion of the spectrum. At long wavelengths, reflected sunlight is negligible. Thermal emission spectra of solid planets detect sharp emission lines are produced at the wavelengths of vibrational transitions when the upper atmosphere is warmer than the surface. Troughs will be present where the atmospheric temperature is cooler than the surface. For gaseous planets, thermal emission spectra detect sharp emission lines are produced at the wavelengths of vibrational transitions when the upper atmosphere is warmer than the lower atmosphere. Troughs will be present where the atmospheric temperature is higher at lower levels. Thermal spectra are taken in the infrared at wavelengths of m.