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Victor Archer | all galleries >> Air Shows 2007, Cable, Red Flag, Riverside, Point Mugu, Minter, Chino, MCAS Yuma, Gillespie, Grass Valley, Camarillo. >> Point Mugu 2007 > IMG_9794.jpg
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01-APR-2007

IMG_9794.jpg

Canon EOS 20D
1/1000s f/6.3 at 200.0mm iso100 full exif

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AmbientEnergy entrepreneur 26-Jun-2009 16:45
It is definitely coming from the water vapor in the air being coaxed to change phase back into liquid form. Yes it is a very fine mist (think cloud diameter droplet), but it is no longer water vapor and has changed phase. This could have been brought about by either the increase in pressure which would have taken an enormous amount of energy to accomplish (like the power of a jet engine driving a 10 ton aircraft through the sound barrier). Or it could have also occurred as a result of the expected decompression occurring just on the other side of the pressure wave. I am betting on the decompression side. As some pointed out in the email thread decompression brings lower temperatures and the dropping of temp lowers the capacity of air to hold water in the vapor form.
Jake 20-Sep-2008 04:25
X-men anyone?
Steve 19-Sep-2008 18:15
"Why does condensation occur? Once the pressure of water vapour in the air exceeds the saturation vapour pressure it is no longer stable. Provided there are dust particles present to act as nucle, the excess vapour over the saturation pressure condenses into droplets. Without nuclei, condensation is difficult and instead the air becomes supersaturated. However, when the supersaturation exceeds a certain critical value water does condense out very rapidly as a mist of fine droplets even though nuclei are absent. This is homogeneous nucleation." - atoptics.co.uk/droplets/iridim31

I've seen clips like this where an aircraft makes a shockwave as it approaches mach 1 and thus the air is compressed in a very small area over a very short period of time. It's possible that this is a different situation here, but the theory behind it is listed above. So there.
TheGreatCO 19-Sep-2008 16:54
Well since you can't see a sonic boom, it's a moot argument. This happens when a plane is turning and the pressure drops so low that the moisture condenses. Pressure drop = temperature drop = higher humidity which means the excess water has to condense out of the air.
MacNCheeze 19-Sep-2008 16:51
Its definitely moisture, they don't fly the planes beyond the the speed of sound at air shows. I don't know what causes it though, sometimes you can see it above the wings near the front in a sharp turn. Maybe some sort of strange air movement.
Guest 19-Sep-2008 16:35
it is moisture dummy...
the shockwave from the jet, compress's the air so much that the moisture forms a cloud
moronhunter 19-Sep-2008 16:12
Its not moisture dummy, its the sonic boom.
Martin 19-Sep-2008 15:34
I think that happens when they move so fast it sucks the moisture out of the air. I have seen this at Air shows and its even more amazing in real life.

*Man I wanna buy one of those $80k migs you always see on ebay.
Jiff Willis 19-Sep-2008 13:27
Dude that is SIC! Perfect image!

Jiff
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