Descriptions:
Edward Gryspeerdt: In a nutshell, ships change existing clouds, making them cool the Earth further, while clouds created by planes warm the Earth.
Ships produce a lot of aerosols but typically emit them low in the atmosphere – this changes clouds near to the Earth’s surface, making them brighter and creating a cooling effect.
Clouds formed from aviation are high up (10km up in the troposphere), and are very cold, making them good at stopping heat leaving the Earth and keeping it warm.
So by producing more of these high-level clouds, aircraft are warming the climate through more than just their greenhouse gas emissions.