Cloudiness levels in Exoplanets Atmospheres

The presence of clouds and hazes has been explored to explain the transmission spectra of several planets observed with the Hubble Space Telescope. They are normally associated with a slope towards the blue wavelengths due to Rayleigh scattering and/or featureless transmission spectra in the near-infrared range (1.1-1.65μm). Understanding the overall level of “cloudiness” in exoplanet atmospheres is particularly important to constrain cloud formation and composition, interpreting the infrared spectra of upcoming observations with JWST, and for planning future exoplanet observations. Here we perform comparative planetology study by analyzing the spectral modulation of the largest uniformly processed sample of exoplanet transit spectra currently available. Using this catalog, we find that exoplanet atmospheres tend to fill the range of available phase space from clear to cloudy with the majority of planets lying in between. Our results suggests that although clouds and hazes are common, most of the planets have detectable spectral features implying in promising detectability of exoplanets atmospheres in future observations.