This is a project jointly funded by the National Science Foundation’s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award recommendation, each Agency funds the proportion of the budget that supports scientists at institutions in their respective countries. Earth’s energy budget is balanced between incoming solar radiation and outgoing thermal energy. Clouds exert a significant impact in both directions, but there has been significantly more study of the impact of clouds on incoming energy from the sun. This project will focus on the opposite route, the emission of longwave, or infrared, radiation from the Earth’s surface and how that radiation interacts with ice clouds in the high latitudes. The impact of this study will be to provide better information to the scientific community on processes that are important for understanding the warming Arctic region. The project will also enhance collaboration between US and UK scientists and provide training for early career researchers. This project addresses three primary research questions: (1) Do current representations of surface properties capture the longwave emission spectrum of snow and ice surfaces corr