These altostratus clouds have wave-like features causing the pattern at the top of the image. Altostratus clouds appear as thin gray or blue-gray layers and are formed by a rising air mass. They are midlevel clouds (6,500-20,000 feet in altitude).
Altostratus clouds (DI02395)
2009-11-09
University Corporation for Atmospheric Research (UCAR)
image
Clouds
NCAR/UCAR Image and Multimedia Gallery
Copyright University Corporation for Atmospheric Research (UCAR). By [insert name of photographer when listed], licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License, via OpenSky. For commercial use contact copyright@ucar.edu.
DI02395
http://n2t.net/ark:/85065/d78050st