Anhang (bibliographische Angaben und Originaltext ) ging nicht mit also dann direkt:
Ludlam, F.H. and R.S. Scorer : Cloud Study. A Pictorial Guide
London: John Murray, 1966 pp 77-78
An aircraft wing lifts the aircraft by producing a ‘downwash’ of air in its wake. At the outer edges of this downwash there are vortices trailing backwards from the wingtips, and on account of the rapid rotation the pressure in the centre of these vortices may be low enough to cause condensation. Wing tip condensation trails… are then formed. Such trails may also be formed at the tips of the propeller blades, particularly when the aircraft is climbing or taking off underfull power. They are then spiral, indicating roughly the tracks of the propeller tips.
Some jet aircraft have engines near enough to the wingtips for exhaust, which contains a high proportion of water vapour, to be drawn into the wingtip vor-tices. A dense wingtip trail is then formed and the cloud-filled vortices can be seen for a mile or two behind the aircraft. The vortex motion delays the mixing of the air in the vortex with the surrounding air, so that trails of this kind are abnormally slow to spread and evaporate.
If an aircraft flies in relatively dry air just above a thin layer of cloud the downwash may penetrate into the cloud forming a dissipation trail …, or distrail, which sometimes consists of a row of clear holes. Under suitable conditions a long strip of cloud along the track of the air-craft may be cleared...
If the surrounding air is cold enough engine exhaust forms a cloud when mixed with it in proportions be-tween certain limits. The cloud so formed, known as an exhaust condensation trail … or contrail is in the region of downwash so that it is extended in a vertical curtain whose lower edge assumes the form of pendulous blobs…
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**~ In Memoriam Ron ~**
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