1Department of Meteorology, University of Utah, Salt Lake City, UT, USA
2Atmospheric Chemistry and Dynamics Branch, NASA Ames Research Center, Moffett Field, CA, USA
3WB-57 Program Office, NASA Johnson Space Center,Ellington Field, Houston, Texas, USA
5Universidad Nacional Autonoma de Mexico, Mexico City, Mexico
6Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA, USA
Abstract. Thin stratiform clouds called pileus can form in the earth's atmosphere when humid air is lifted above rising convection. In the lower troposphere pileus lifetimes are short, so they have been considered little more than an attractive curiosity. This paper describes pileus cloud forming near the tropopause at low-latitudes, and discusses how they may be associated with a redistribution of water vapor and ice at cold temperatures.