Aviation Non-CO2 Radiative Forcing & Tactical ISSR Flight Level Optimization Engine
Contrails only persist and evolve into warming cirrus clouds when the ambient air is supersaturated with respect to ice (RHi > 100%) and colder than -40°C. These pockets are surprisingly shallow—often only 1,000 to 2,500 feet thick vertically—allowing simple step-climbs or descents to avoid them completely.
During the day, contrail cirrus reflects incoming solar radiation (shortwave albedo cooling) while trapping outgoing terrestrial infrared radiation (longwave warming). At night, there is zero solar reflection, turning nighttime contrails into pure greenhouse heaters with 3× to 5× the warming intensity per kilometer.
The Schmidt-Appleman Criterion calculates the thermodynamic mixing line between hot exhaust moisture and freezing stratospheric air. Because contrail radiative forcing acts immediately and CO2 accumulates over centuries, avoiding a 500-mile contrail for a mere 0.8% fuel penalty yields a 40:1 net cooling dividend on a 20-year horizon.