Central Idea

Residents in the Arctic have witnessed an extraordinary atmospheric display of Polar Stratospheric Clouds (PSCs).

Polar Stratospheric Clouds (PSCs)

	Details
Formation and Location	Form in the polar stratosphere at altitudes of 15,000–25,000 meters; common over Antarctica and the Arctic.
Temperature Conditions	Require extremely cold temperatures, typically below −78°C (−108°F).
Types	Type I: Composed of water and nitric acid. Type II: Made almost entirely of water ice.
Role in Ozone Depletion	Facilitate chemical reactions that produce chlorine and bromine compounds, leading to ozone destruction.
Appearance	Iridescent, shimmering pastel colors, leading to their nickname “nacreous” or “mother-of-pearl” clouds.
Observation	Visible during twilight, illuminated from below by the Sun.
Research and Monitoring	Studied for impact on ozone depletion and climate change; monitored via satellites and ground stations.
Environmental Concern	Linked to human-made chemicals like CFCs; subject to international regulation like the Montreal Protocol.
Climate Change Connection	Research ongoing into how climate change might affect PSCs’ frequency and distribution.
Discovery and Study History	Observed since the 19th century; their role in ozone depletion understood in the 1980s.