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

=== Assistant: Absolutely, let's delve into the scientific literature that examines the factors influencing ice supersaturation ISS an… ===
Absolutely, let's delve into the scientific literature that examines the factors influencing ice supersaturation (ISS) and relative humidity with respect to ice (RHi) at flight altitudes. These studies provide insights into the formation and persistence of ice clouds, which are crucial for understanding contrail formation and their climatic impacts.Nature<ref>{{cite web|title=Nature|url=https://www.nature.com/articles/s41598-024-75756-9|publisher=nature.com|access-date=2026-01-02}}</ref>

===== 1. Towards a More Reliable Forecast of Ice Supersaturation This study introduces a new ice-cloud scheme that explicitly models the decay of in-cloud humidity, aiming to improve the reliability of ISS forecasts. =====
# A Statistically Significant Increase in Ice Supersaturation Analyzing data from 1979 to 2020, this research finds that while the mean upper tropospheric humidity with respect to ice (UTHi) increases at about 0.15% per decade, higher UTHi values (exceeding 70%, 80%, 90%, and 100%) increase at faster rates, suggesting more favorable conditions for cirrus and contrail formation in the future.
# Ice Supersaturation Variability in Cirrus Clouds: Role of Vertical Wind Speeds This study examines how ice supersaturation and cirrus properties respond to changes in vertical wind speeds, highlighting that cloud-scale wave motions significantly influence the frequency of ISS states.
# Ice-Supersaturated Air Masses in the Northern Mid-Latitudes Investigating air masses with RHi > 100%, this research notes that such regions often result from decreases in temperature or increases in water vapor mixing ratio, emphasizing the dynamic nature of ISSRs.
# Ice Supersaturation and the Potential for Contrail Formation in a Changing Climate This paper discusses the occurrence and duration of ISS conditions, noting that a significant portion of ice-supersaturated air parcels can remain in that state for extended periods, which has implications for contrail persistence.
# Ice Supersaturated Regions: Properties and Validation of ERA-Interim Data This study compares in situ measurements of RHi with reanalysis data, aiming to validate and improve the representation of ISSRs in climate models.
# Distributions of Ice Supersaturation and Ice Crystals from Airborne Observations Through case studies, this research demonstrates that ISS formation is influenced by mesoscale uplifting, small-scale waves, and turbulence, providing a nuanced understanding of ISS dynamics.
# Shallow Cirrus Convection – A Source for Ice Supersaturation This study investigates the impact of local dynamics, such as shallow convection within cirrus clouds, on the occurrence of high ice supersaturation, suggesting that internal cloud processes can sustain ISS conditions.

===== - 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>

===== The formation and persistence of ice supersaturation at flight altitudes are governed by a complex interplay of atmospheric dynamics, thermodynamics, and microphysical processes. The studies highlighted above provide a comprehensive understanding of these factors, contributing to improved forecasting of ISS conditions and their implications for aviation and climate. =====

If you're interested in a more detailed exploration of any specific aspect, such as modeling approaches or observational techniques, feel free to ask!