Clouds Formation Before The Storm

• Polar stratospheric
Nacreous clouds occur most typically at altitudes of 15,000–25,000 m (50,000–80,000 ft) during the winter when that part of the atmosphere is coldest and has the best chance of triggering condensation. Also known as mother of pearl clouds, they are typically very thin with a cirriform appearance. Nacreous clouds are sub-classified alpha-numerically based on chemical makeup rather than variations in physical appearance.
- Type 1: Nacreous containing supercooled nitric acid and water droplets.