High level clouds....sort of!

These unusual formations occurred a few weeks back. They appear to have formed out of old aircraft contrails following the passage of several aircraft on a similar routing. However it was complicated by those trails passing through a number of existing cirrus clouds. The end result, if perhaps partly man made, is still quite spectacular.

Contrails

These are produced by high flying aircraft. Their shape and form (and whether they form at all) depends on the atmospheric conditions at the time. The basic science of it is that the hot exhaust gasses mix with freezing air typically around -40 to -50C. The moisture generated turns into ice crystals which cause the thin linear clouds that we know as contrails. How long the trail is and how long it lasts depends on the air temperature and humidity. Interestingly they are now generally recognised as a cloud type, albeit manmade.

This picture was taken looking north west from our house. One can only guess as to the reason for the somewhat artistic manouevre undertaken by the aircraft on the right!