BeCoM

One of the most obvious and significant non-CO2 effects is the formation of visible contrails, which can grow into long-lasting contrail cirrus clouds in ice supersaturated regions. The prevailing meteorological conditions (in particular temperature and humidity) have a decisive influence on the atmospheric lifetime of contrails. Depending on the radiation conditions (zenith angle of the sun, other clouds and brightness of the ground), contrails can have a warming or cooling effect, as they both scatter solar radiation back into space and thus cool, as well as retain radiation emitted from the earth's surface in the atmosphere. Depending on the type of aircraft, flight region, altitude, time of day and current weather, the climate effect of a contrail can therefore vary greatly. Averaged over the globe and day and night, however, contrail cirrus lead to a significant warming of the atmosphere.