About 40 years ago, back when I was in 6th grade, my friend and I went off to summer camp at Camp Arcade in California's Sierra Nevada mountain range. At one point, the camp was divided into two groups for an overnight hike. My group went to a lake, and the other went to a nearby hill or rock formation that I think was called Devil's Head or something like that because it sort of resembled a demonic face. Anyway, in late afternoon, we spotted a white streak moving across the sky in our general direction. To our surprise, it seemed to explode over Devil's Head with a loud boom and formed a huge "halo" of smoke that lasted for quite some time. Needless to say, it was a pretty strange experience. I remember someone suggesting that it was a rocket test, but it seems odd that would happen as far inland as we were. I thought it was some giant firework set off by the other group, but my friend assured me that they didn't know anything about that.

I was reminded of this recently, and it got me to wondering what exactly I saw that day. Are meteors or comets known to create that kind of large ring?

Clouds form spontaneously when air reaches the necessary pressure/temperature. Near mountains you will often see clouds trailing from peaks as air is forced by the lay of the land to the necessary altitude, they also often disappear if the air mass then decends in altitude. Such rings around the top of peaks normally require very low wind speeds and a local change in air pressure to cause uniform ring-shaped cloud formation. I suppose that the shockwave of a jet's sonic boom caused the cloud formation because the air was already very near the critical point.

__________________
"Those who cannot remember the past are condemned to repeat it" - George Santayana

Hi

Your post remember me of a stunning picture of a jet breaking the sound barrier. See below this link :
http://www.rense.com/general8/boom.htm

I hope it will help you , don't know.

Cheers

These clouds are pretty small and travel with the aircraft, however.
What the OP describes sounds like a large, stationary affair.

Grant Hutchison

Well, supersonic flights were not uncommon in Northern California in those days, so that might be it. Perhaps the streak was a jet contrail, but I don't think that would have attracted anyone's attention the way it did--we were all looking at it before the boom. The streak seemed brighter, and didn't extend back to the horizon. Plus, the streak did not continue past the point where I heard the boom and the ring started to appear.

Do you have any links to pictures of these formations?

It was a long time ago, so I'm not sure, but as I recall, the ring got extremely large and dissipated over a fairly long period of time (maybe 10-20 minutes?)

If you can remember enough details, we could have a fairly good
chance of identifying what kind of thing you saw. But it sounds to
me like it would require a lot of questions and answers to rule out
a large number of possibilities. The brightness of the sky, brightness
of the streak and of the halo, length and width of the streak, speed
of the streak across the sky, size of the halo, and on and on.

The fact that you were in an unusual situation (for you) suggests
that it was most likely an ordinary phenomenon that you hadn't
seen before because you were new to the place.

-- Jeff, in Richfield, MN

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

__________________
"Those who cannot remember the past are condemned to repeat it" - George Santayana

Nice site!

The closest one to what I saw is the Mt. Ranier one by Ed Book (the sixth image from the top). However, what I saw was:

-not nearly as large (it only took up about 20% of my field of view)
-much better defined
-appeared in an otherwise cloudless part of the sky
-appeared well above the rock formation, rather than around it
-was proportioned more like a bicycle tire than a doughnut

Since this occurred so long ago, it would be very difficult to provide those kinds of details. The best I can do is:

-I believe the sky was fairly clear
-It was late afternoon
-The halo brightness was about what I would have expected from a cloud or white smoke
-I don't recall the streak brightness so much as the fact that it didn't look like an everyday thing (such as a jet contrail). My impression at the time was that it was a rocket plume or the trail of something entering the atmosphere.
-The streak moved quite a bit faster than a commercial jet at cruising altitude. The elevation there was about 7000 feet, though, so that might affect things. If it was a jet, it would have to have been a military one, and perhaps it could have been flying much lower than a regular jet.
-The halo size is very difficult to estimate since I don't know how far away it was. I was standing near a lake, and the rock formation was on the opposite side. I would say that I was looking up at it at about a 30-45 degree angle. The halo began very small, and spread out over the course of a couple minutes. Before it started to dissipate, it looked a bit like a bicycle tire in terms of proportions.

The only other thing I recall about the incident is that one of the camp counselors said something like "Tell Vandenberg they were right on target" which made me think it was a rocket. However, what I didn't know at the time was that Vandenberg AFB is located on the coast about 300 miles south of where we were (Lake Tahoe), so it's not like we were in the neighborhood.

Thank you GORT
These were incredible.

I wonder if the Sun might have been hidden behind Devil's Head, and
what you saw was a circle of light reflected from aligned ice crystals
above the mountain. The ice might have condensed from water vapor
in the air because of the passage of whatever made the streak, or
it might have been there by coincidence.

Here's a simple diagram of a fairly common type of halo made by the
Moon or the Sun, showing the relative size of the ring in comparison
to the size of the Moon or Sun, which I made for a similar question
in 2005:

http://www.freemars.org/jeff2/halo1.png

-- Jeff, in Richfield, MN

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Sounds like you're describing a sun dog? http://www.und.edu/admin/

If so, the thing I saw wasn't anything like that. It was like a giant smoke ring, and it was at a flatter angle.

I went ahead and did a rough sketch of what I recall. It really was an odd scene.