cirrus clouds . [6] ___________________________________________  5. Nacreous Clouds ( Nacreous Clouds - Antartica) Source: Per-Handre Hoffmann Also called mother-of-pearl-clouds or polar stratospheric clouds. These are  clouds  in the winter polar  stratosphere  at altitudes of 15,000–25,000 meters (49,000–82,000 ft). ___________________________________________  6. Sky Punch / Punch Hole Clouds Source: Meteorology News A  fallstreak