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[den]

Comments

Re:

[level-head.livejournal.com]

The high altitude phenomena that Batty pictured, and that I was describing, are called both "contrails" and "vapor trails" -- the literature does not distinguish one of these as the low altitude effect of heavy wing loading on humid air near the dew point.

That's an interesting process to watch, and very pleasant -- but the resulting clouds are not long lasting.

The contrails/vapor trails that cross the sky at altitude are exhaust-driven (and airflow-shaped) from everything that I have observed and read on the topic.

===|==============/ Level Head

[acelightning.livejournal.com]

[dewhitton.livejournal.com]

You can see the exhaust trail forming in a 747 if you go to the last window and look back. I could see the first fingers of condensation around the outside of the stream chasing the plane.

[acelightning.livejournal.com]

[kelloggs2066.livejournal.com]

I recall seeing a lot of paintings of the contrails coming off the engines of B-17s. There are undoubtedly wingtip vortex created contrails, but they're much smaller than the engine particle created contrails. I would guess that the atmospheric conditions which allow them to form is probably farther from the norm than the engine contrails.

Scott (Not a meteorologist) Kellogg

[level-head.livejournal.com]

If you see pictures of aircraft at altitude -- and we have a number of military aircraft pictures floating around now due to recent activity -- you can see that these are indeed exhaust-triggered rather than wake vortices.

As a general rule, the faster the aircraft is flying, the less severe the wing vortices are. The FAA is only really concerned about them when the heavy aircraft are low and slow, briefly after takeoff and for some time on final approach.

There is always some tip votice activity -- you may have seen a number of recent aircraft with "winglets" on the ends of the wings to squeeze a bit more out of this wasted energy -- but it is less dramatic, has a slower rotational speed, and stays around for a shorter period of time at cruise altitude.

It is possible to get "squeeze clouds" at altitude, but the conditions that support it are much more rare. Contrails, however, are very common.

===|==============/ Level Head

[kelloggs2066.livejournal.com]

Ooo!

Wonderful Book! :D

Scott