The absorption of electromagnetic radiation within a cloud. With some exceptions, clouds typically absorb ≈10% of the (broadband) shortwave radiation and ≈95% of the longwave radiation incident on their boundaries. Thin clouds, notably thin cirrus, may absorb considerably less. The dominant absorber tends to be the water droplets or ice crystals making up the cloud, with water vapor playing a matching role only for shortwave absorption by upper tropospheric clouds.