A photo of a sonic boom.

[Bass]

Dude you're confusing me, a task I like to reserve for myself, when the sun's below the yardarm, (and that's just plain bewildering). Time to look instead of shooting from the hip... .

Agreed!
Besides, it's band practice night and I need to go and get some beer.
Until the morrow.....................

[Bass]

I figured it out on the way home.
Honestly. some days I think that my brain has taken a sabbatical.
We had the effect of pressure reversed. The effect of increasing pressure is to REDUCE the humidity at which saturation occurs (or increase the RH).
However the other key factor is that the effect of temperature on saturation is MUCH more pronounced than the effect of pressure and this is important.
So when we compress air in the compressor, it wants to reject moisture. But it doesn't happen immediately because the increased temperature overrides it. So it's pretty much as you said and the water is squeezed out in the receiver when the air cools.

Well, how do we get condensation in the LOW pressure area behind the shockwave (a la Ranty Dave)? If the pressure is reduced, then it should hold MORE water, not less.
Again it's the temperature effect overriding the pressure effect.
A shock wave has some pretty vigorous pressure changes, and I will bet my left bollock (I've had the sports model conversion, so that's not as big a wager as you might think), that if we could put a thermometer in the low pressure area behind the shock wave, that we would find that the temperature momentarily drops low enough that the air goes below its dewpoint, despite the pressure change pulling it the other way.

The clues were all there. Terbang mentioned the temperature drop with pressure. I said that the saturation humidity changed rapidly with temperature and you suggested that the higher air pressure effectively squeezed the water out.
Just took a while to put it together.
Sorry about that.
Just to complete the picture, it also explains why I only see condensation trails off flap tips when the RH is really close to 100%. It also means that you need drains around your compressed air reticulation because the air is cooling, not because the pressure is dropping.

PS Just looked at your web reference, only to discover that I've largely repeated what he said.

[R6_kid:Me]

A few more picks..

heh, the F-14 really does know how to do things the best!

[terbang]

Here is what Meteorologists and Aviation people refer to as the Adiabatic process to explain a lot of what happens in the atmosphere.

[Korumba]

heh, the F-14 really does know how to do things the best!

I agree with that.

[avgas]

So correct me if i'm wrong but velocity of the air is irrelevant of the pressure? As i thought the 2 were linked when you involve a surface.
Also what about the roll off effect of the air curling back on itself after it hits the jet? does this condense all the air around the jet.....hense the big halo?

[Skyryder]

Well it's nice to know that the geeks have a bit of competition.

Skyryder

[peasea]

Vapour trails and wing tip vortex are not the same. Vapour trails, the ones you see way up in the atmosphere are produced by an aircrafts engines. These would be more correctly called Ice crystal trails as they consist mainly of Ice crystals. I have climbed through many 'vapour trails' in the troposphere and, like cirrus clouds, you can hear a 'rustling sound' over the cockpit as you pass through them. Climbing further into the stratosphere (in a Gulfstream not a Boeing) I notice that our own 'vapour trails', viewed from our own external vigilance cameras, don't exist anymore.
The, sometimes visible, tip vortex is created as a 'byproduct' of lift. Mainly at low speed. The wing tip vortex is actually considerably larger than the core that you often see, as much as half of the aircrafts wing span. Wing tip vortex has extremely high local velocities that are root of the wake turbulence danger that we are faced with every day. Wing tip vorticies also add to the aircrafts drag profile and much effort is put into reducing it wirh all sorts of devices like winglets, fences and so on. Nice picky here of a light aircraft using smoke to highlight the vorticies.



Not only do winglets serve to decrease drag, thus increasing range, but they also look damn sexey.

I wish I had a plane with winglets. I'd invite my favourite kb'ers to come party on it with crates of Champers, a handful of hookers and saucerfuls of cocaine. Ahh, the good old days.