Contrail

Contrail (condensation trail) is a visible trail of ice crystals formed behind an aircraft at high altitude when hot, humid exhaust gases mix with the cold ambient air. Contrails form when the temperature is below approximately -40°C and the air is sufficiently humid.

Types:

• Short-lived: Dissipate within seconds (dry air)
• Persistent: Remain visible for hours in humid air, spreading into cirrus-like clouds

Persistent contrails can affect regional climate by trapping heat (greenhouse effect) and are a subject of ongoing aviation environmental research.