10/22/2004: Contrails over southern US

I thought this image of contrails, the condensation left by jets as they fly, was pretty interesting. But some people think it's a massive conspiracy bent on raining pollution down from the skies. In fact the web seems chock-full of such hand-wringers thinking that they're changing the weather or spraying mystery chemicals. But don't worry, there are also people who will sell you stuff to keep you safe from all this.

But some people think it's a massive conspiracy

Oh, no. Not those people. Anybody but those chemtrail idiots! If there is any conspiracy theory that I cannot stand, its people that think vapor trails crossing in the sky over their city is an indication the the government is trying to control their minds.

You forgot the bit about the contrails being responsible for global warming ...

My boss had that image as his desktop background for a while last week.

My initial feeling was this was a faked image as the scale would suggest that the contrails are 10s of miles wide.....but scanning out there I see this picture of contrails over the English Channel. Still doesn't seem right...why don't they show up on the visible light weather satellite images?

FD

Here's a stumper.. how do they show up at all? Shouldn't we just be seeing clouds there? How do they photographically filter the weather out?

You don't see them on normal satellite images because: the weather isn't always optimal for their formation and the satellite images you see on normal weather programs are over such large areas that they are rarely visible. Sometimes, though, they are -- a lot of the cirrus clouds you see are the remnants of contrails that have been scattered and spread out by the wind.

And I don't think they're filtering any weather out in these images -- you can still see clouds in them. My guess is that they took the images during the colder winter months when the air is mostly clear and jet contrails not only tend to form easily, but also tend to stick around for almost the entire day, spread out, etc. During many of the winters I spent in Atlanta you could look up and see nothing but the contrails for all the traffic coming into and out of Hartsfield.

Usually, contrails smear out and fade away. However, when atmospheric conditions are just right (the ice crystals that make up the contrails stay relatively in place due to proper temps or lack of high winds at their level), they will spread out widely (yes, up to tens of miles) and just hang there...

They're just artificial clouds, after all...

September 11 provided a rare oppurtunity to perform scientific research. Based upon satellite data, if was concluded that contrails actually reduce global warming.

I don't know Jack about contrails, but my observation is this: Evidently they are controlled by altitude and/or weather conditions. I thought they were a visual sign of acceleration or deceleration. They show up more on this image in areas far from airports, thus blowing that theory away. They probably are most visible during ascent or descent, approaching or departing a terminal.
I thought I saw a traffic light right on the Ga. / Fla. line. Good luck going through Customs.......................don't wear the rag.........

Help me please!I seem to be living right in the middle of this contrail conspiracy?
I saw that traffic light too. However it was25 years ago traveling u.s.1 from Waycross thru Folkston which happens to be the last town prior to reaching the Fl. line. It's funny it was always on sunday that I passed thru that light.
I get it now they didn't sell beer in Ga. on sunday. You know it's funny, I don't ever remember the traffic light onthe way back. It must of been the flowers we found in the cow pasture, Damn those flowers. They always seem to keep reality at a distance. Guess what,that traffic light is still there. It's probably a younger one with all those damn hurricanes.

Help me please!I seem to be living right in the middle of this contrail conspiracy?
I saw that traffic light too. However it was25 years ago traveling u.s.1 from Waycross thru Folkston which happens to be the last town prior to reaching the Fl. line. It's funny it was always on sunday that I passed thru that light.
I get it now they didn't sell beer in Ga. on sunday. You know it's funny, I don't ever remember the traffic light onthe way back. It must of been the flowers we found in the cow pasture, Damn those flowers. They always seem to keep reality at a distance. Guess what,that traffic light is still there. It's probably a younger one with all those damn hurricanes.

TW -- you mean like this?

Three things produce vapor trails off a plane, I think. The engine exhaust, "sharp" edges (like winglets, flap edges, etc) that produce vortices, and the lifting edge of a wing, which produces pressure low enough to create condensation.

Here's one from the low pressure off the wings.
...and nothing is cooler than the sound barrier shockwave.

the shock wave picture is awesome! never seen anything like it before, thanks !!