How to recognize a contrail
A young contrail is usually straight or gently curved, narrow, and aligned with an aircraft path. It may appear as paired lines before turbulence merges them. In cold, sufficiently moist air aloft, a trail can persist, broaden, shear, and become difficult to distinguish from natural Cirrus.
Typical level
Usually high, near cruising altitude.
Main texture
Linear when young; broader and fibrous as it spreads.
Taxonomy note
Contrail is not one of the ten WMO cloud genera.
Model label
Ct · output index 6
Field clues and lookalikes
- An aircraft at one end or multiple parallel trails support a contrail identification.
- Cirrus can also form straight-looking bands, so one still image may not reveal origin.
- Persistent trails can spread until their original linear form is no longer obvious.
Why PictureCloud includes it
The CCSN dataset used for the baseline classifier contains a Contrail class alongside ten natural genera. PictureCloud preserves that exact output order for model compatibility while clearly separating the label from WMO genera.
Photography notes
Include the full line, its ends, and surrounding sky. A close crop of a spreading section may be scored as Cirrus or Cirrostratus.