Pluto's main atmospheric species, N2, is also frozen on its surface, as are its minor atmospheric species, CH4 and CO. The New Horizons spacecraft found complicated and intriguing evidence for a dynamically interacting surface and atmosphere. The REX instrument shows a planetary boundary layer that depends on whether there's N2 ice available to sublimate.
Altitude appears to be a factor in the distribution of both N2 and CH4 ice, with N2 favoring lower altitudes (higher pressures, so higher condensation temperatures), whereas some high ridges are coated in CH4 frost. Sublimation may be responsible for some of the stranger geologic forms on Pluto. Finally, preserved landforms may point to earlier ages with more widespread volatile ice coverage or higher surface pressures.
Dr. Young will talk about the evidence, and some of the ways New Horizons is influencing how we think about Pluto's atmosphere and surface.