Nice and thanks very much. I was unaware of this effect until I saw it posted on CR4 a few weeks ago. The things you learn here, eh? (Not even including all the "What Is It?" challenges.)

Just out of curiosity, when such an effect forms around a plane, does it travel along with the plane throughout it's (I assume) extremely brief existence? Or does it form and the plane moves on without it, leaving behind either nothing or a bitty cloud?

Hi Guest - feel free to register so we get to know ya..._{(or are you lurking)}

I've only seen this happen once @ an air show in CA - the vapor cloud very quickly dissipated...

Cheers!

Thanks for the pictures. I am told Ft. Lauderdale will get it's air show back again in 2010. They never get too close to that speed though, too many high rise buildings with windows near.

thankz for the cool pic's

I received this from a friend back in 2000. It came with a copy of the first picture in this post. Pretty interesting. (I can seem to attach the picture, but on close scrutiny and comparison of the cloud structure it is the same)

Every so often, just the right combination of conditions and events occur to create an unbelievable event-in this case an F-18 passing through the sound barrier. Not only were the water vapor, density and temperature just right, but there just happened to be a camera in the vicinity to capture the moment. The F-18 is actually in transonic flight, with normal shock waves emanating from behind the canopy and across the wings and

fuselage. The condition will last for only an instant, and once supersonic flow exists completely around the aircraft, sharp-angled sonic cones replace the normal shock waves. The odds of getting a shot like this are staggering.

There's an invisible shockwave coming off the nose which contains the 'boom' of crossing into supersonic flight. This shockwave has higher-than-ambient pressures, keeping the humidity in the air as an invisible gas. Immediately following this shockwave though is a low pressure region. A drop in pressure make a drop in temperature which condenses the humidity in the air into a 'cloud' that make this tutu around the aircraft.

You get the same effect anytime there's a rapid drop in pressure. A good thing to verify this weekend. Pop the top off of a chilled beverage in a pressure vessel (in a can or bottle obviously) and you'll see a small cloud of condensed vapor come out. Turn on the bbq and the depressurizing tank will begin to cool...condensing water onto it and even making ice if you do it long enough (but mostly happens just on those small gas canisters for portable stoves or grills). Repeat several times this weekend and report your results back here.

Bring on the summertime science!

Wow, Thanks a lot.

When I was a kid in Jonesboro Arkansas we must have been in a test flight zone since sonic booms were common events.

Tchotchkes fell off their shelves.

Was probably 1957.

Last time I was at an Air Show in Wilmington NC, Warthogs and F 16s flew over low to the crowd, and all the babies started crying.

It was sort of funny in a sick sort of way, like when I was at the rodeo and standing by the chickenwire fence and a bull fell against it.

Early memories of abject fear are sweet.

Extremely great photos in my opinion. Would make a great calendar.

Funny how when I was a kid, it seemed like nothing much bothered us.

Sonic Booms, Cool!, DDT truck fog, Wow, what fun!

Rabid dog snapping at us by the ice cream truck and Sheriff Bob was there with a rifle in 5 minutes, an shooting it dead at the end of the street.

Cottonmouth sunning on the porch, and 5 ladies beat it flat with shovels.

-And for fun, we threw rocks at each other.

What the Hell, the Cold War had its charms...