Definition
A clear lane or rift carved through an existing cloud layer by an aircraft passing through it. The aircraft's exhaust heat and the mixing of drier air evaporate the cloud droplets along its path, leaving a visible cloud-free trail. Often called a 'distrail.'
Plain English
When an aircraft flies through a thin cloud layer, it can punch a clear gap through the cloud, leaving a visible empty trail behind it. It is the opposite of a contrail — instead of a cloud being created, a cloud is removed.
Context Anchor
Seen in weather and cloud discussions, especially when an aircraft flies through a thin cloud layer and leaves a clear streak behind it.
Derivation
From 'dissipation' (Latin 'dissipare,' to scatter or disperse) plus 'trail.' The cloud is dispersed along the aircraft's path. The shortened form 'distrail' is built the same way as 'contrail' (condensation trail), which helps signal the contrast: contrails add cloud, distrails remove it.
Why Pilots Care
Distrails are uncommon and mostly visual curiosities, but recognizing them helps a pilot interpret cloud behavior and aircraft effects on thin layers — useful for situational awareness and weather observation.
Grounding Statement
Picture an airplane cutting a narrow, temporary clear line through a thin cloud, like a finger making a line through fog on a window.
Intuition Check
Do not think of a dissipation trail as a trail of smoke or added cloud. It is usually the opposite: a clear or thinner path where an existing cloud has been reduced.
Example Sentence 1
From the ground, the high cirrus layer showed a long dissipation trail where a jet had cut through it minutes earlier.
Example Sentence 2
Dissipation trails appeared over the airport after several planes took off through low clouds.