Editing Openai/680a25f8-9f18-8004-a42d-cd36374ba000 (section)

===== - Relative Humidity with Respect to Ice (RHi): At high altitudes, the air can become supersaturated with respect to ice, meaning RHi exceeds 100%. This condition is essential for the formation of ice clouds and contrails.ACP<ref>{{cite web|title=ACP|url=https://acp.copernicus.org/articles/20/8157/2020/|publisher=acp.copernicus.org|access-date=2026-01-02}}</ref> =====
* Typical RHi Values: While RHi values exceeding 100% are necessary for ice cloud formation, values as high as 140–160% are considered extreme and less common. Such high supersaturation levels are often transient and influenced by specific atmospheric conditions.
* Factors Influencing ISS: - Vertical Wind Speeds: Updrafts and gravity waves can transport moisture to higher altitudes, promoting ISS. - Temperature Fluctuations: Cooling of air parcels can lead to supersaturation if the temperature drops below the frost point. - Aerosol Concentrations: The presence of aerosols can provide nucleation sites for ice crystals, affecting the persistence of ISS.NOAA Repository<ref>{{cite web|title=NOAA Repository|url=https://repository.library.noaa.gov/view/noaa/64001/noaa_64001_DS1.pdf|publisher=NOAA Repository|access-date=2026-01-02}}</ref>