Trailspotter
Senior Member.
Last week, on Thursday 9 July 2015, I took a few pictures of an aerodynamic contrail in Dublin, Ireland:


It was produced by an Aer Lingus A320 that was still climbing from 28,000 ft to 29,000 ft at the time:

It was a purely aerodynamic contrail, however, it resembled an ordinary exhaust contrail in a number of aspects. It was so thin in the beginning that there appeared to be a gap between the plane and its trail. The trail's density increased with the distance from the plane and was shaped by the wake vortices into two parallel tubes merging together at the distal end:

Initially the trail was right overhead and therefore looked rather long, but I could see its both ends where the plane entered and exited the layer of ice-supersaturated air. The following evolution of the trail was rather conventional, with pendules forming due to the Crow instability:


The trail was gradually spreading out while carried away by the wind, with its lower (left) end getting denser, presumably because of a higher absolute humidity than at its higher (right) end:


A few minutes later I spotted another aerodynamic contrail left by a heavier A340 at 32,000 ft:


This was a mixed contrail, with the exhaust plumes of both inner and outer engines being visible behind the plane, and it was evolving in a similar way before being obscured by low clouds:

It was produced by an Aer Lingus A320 that was still climbing from 28,000 ft to 29,000 ft at the time:
It was a purely aerodynamic contrail, however, it resembled an ordinary exhaust contrail in a number of aspects. It was so thin in the beginning that there appeared to be a gap between the plane and its trail. The trail's density increased with the distance from the plane and was shaped by the wake vortices into two parallel tubes merging together at the distal end:
Initially the trail was right overhead and therefore looked rather long, but I could see its both ends where the plane entered and exited the layer of ice-supersaturated air. The following evolution of the trail was rather conventional, with pendules forming due to the Crow instability:
The trail was gradually spreading out while carried away by the wind, with its lower (left) end getting denser, presumably because of a higher absolute humidity than at its higher (right) end:
A few minutes later I spotted another aerodynamic contrail left by a heavier A340 at 32,000 ft:
This was a mixed contrail, with the exhaust plumes of both inner and outer engines being visible behind the plane, and it was evolving in a similar way before being obscured by low clouds:
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