Weird black ring appears in the sky [Pyrotechnic Smoke Ring]

[Jason]

http://sploid.gizmodo.com/a-weird-black-ring-appeared-in-the-sky-in-england-and-t-1563234883
Has anyone seen this? I was fooling around on the net and came across this photo. Apparently a 16yr girl took this in her backyard in England. No one has the faintest idea of what this could be, so I thought I would bring it to the experts on this forum for their opinion. Could it be some type of locust or insect that is swarming. I've seen certain species of ants do this sort of shape (follow the leader)? Or what else could it be?

 

[Mick West]

It's a smoke ring from a pyrotechnic device at Warwick castle:

http://www.bbc.com/news/blogs-magazine-monitor-27037579

The eventual answer came in the middle of Tuesday afternoon when a statement from Warwick Castle confirmed that they had been testing fireworks.

A Warwick Castle spokesman said they had been testing "fire effects" to go with the daily firing of the Trebuchet Fireball - a giant catapult.

"We've seen a number of different effects, including the vortex images that have been reported," the spokesman said.

A smoke ring is formed by fireball type explosion - typically a fuel-air burn, with gasoline. The relatively low speed burn creates two things: Smoke, which ends up in the ring, and heat, which creates the rapid upwards motion, and creates the vortex around the edge of the column of rising air. It starts out like this. Notice the fireball has risen quite a bit from the source, and the rotation is already apparent around the base.

Here's a more detailed look at the entire process from a smoke-ring making machine:



And another from just a simple home-made explosive mix. Notice it's not a simple explosion - it's a relatively slow burn, which gives it the upwards motion, and then the vortex.


These smoke rings probably happen quite a lot in pyrotechnic displays. BUt those displays are usually at night, so you don't see the ring. You saw it here because they were testing it in the daytime.

 

[Jason]

It's a smoke ring from a pyrotechnic device at Warwick castle:

http://www.bbc.com/news/blogs-magazine-monitor-27037579

The eventual answer came in the middle of Tuesday afternoon when a statement from Warwick Castle confirmed that they had been testing fireworks.

A Warwick Castle spokesman said they had been testing "fire effects" to go with the daily firing of the Trebuchet Fireball - a giant catapult.

"We've seen a number of different effects, including the vortex images that have been reported," the spokesman said.

A smoke ring is formed by fireball type explosion - typically a fuel-air burn, with gasoline. The relatively low speed burn creates two things: Smoke, which ends up in the ring, and heat, which creates the rapid upwards motion, and creates the vortex around the edge of the column of rising air. It starts out like this. Notice the fireball has risen quite a bit from the source, and the rotation is already apparent around the base.

Here's a more detailed look at the entire process from a smoke-ring making machine:



And another from just a simple home-made explosive mix. Notice it's not a simple explosion - it's a relatively slow burn, which gives it the upwards motion, and then the vortex.


These smoke rings probably happen quite a lot in pyrotechnic displays. BUt those displays are usually at night, so you don't see the ring. You saw it here because they were testing it in the daytime.

It's truly amazing, and I wonder what physics are at play in order to keep that smoke ring formation. It's weird that the 16yr girl made no mention of the pyro. It was probably audible from where she was because the formation was there for a good 30seconds plus.

 

[Soulfly]

It's truly amazing, and I wonder what physics are at play in order to keep that smoke ring formation. It's weird that the 16yr girl made no mention of the pyro. It was probably audible from where she was because the formation was there for a good 30seconds plus.

I believe this helps explain it.
http://en.wikipedia.org/wiki/Vortex_ring
Or.
http://en.wikipedia.org/wiki/Vortex_ring_gun

 

[Mick West]

Amusing history there:

Vortex rings must have been known for as long as people have been smoking,

A vortex ring is somewhat related to the wingtip vortex that leads to the hybrid contrail, and the crow instability loops and twists.

Although the mechanism of creation is radically different.

 

[Mick West]

Another smoke ring, this time from a transformer explosion:
http://wtnh.com/2016/05/26/transformer-explodes-near-branford-train-tracks/

Branford Fire responded to 137 Meadow Street on Thursday evening for a fire. An Amtrak transformer exploded around 7 p.m., sending burning oil onto a boat, building, and truck, destroying the boat and truck, and causing minor damage to the building.
[...]
Report It photos sent in to News 8 show the transformer fire near the Branford train tracks. More photos sent in show a large, black ring of smoke hovering over the sky. The ring is likely a result of the explosion.