Well, I'm normally one to debunke a story with a plausible explanation - but aside form the purple picture posted (huzzah for alliteration by the
way), I can't think of anything that would cause this kind of a sighting.
First, it wasn't during the evening, as the sun was still setting, but was rather during the night you said. That's the real catcher. That purple
cloud event that was pictured only occurs during an evening. Since you said it was BRIGHT Purple, far brighter than the sky around it, that also adds
weight to it being a true UFO sighting. If you could please be very specific if it was night (as in, black sky), and not just a dark dusk or twilight.
Accuracy is essential for pinpointing whether this is a true UFO sighting, or, as those who deny ignorance, if it is just a rare, intriguing, but
Next, the speed that it moved at sounds interesting. Was it moving in the direction of the wind? Or against? If it's against the wind, it adds to it
being a UFO, if it's with the wind, it adds to it being a cloud. Please be truthful here. If you don't know, just say "I can't remember
exactly/for sure" and it goes in the neutral book.
Next, the "boiling" statement you make sounds intriguing to me. I'd really like to know what you mean by "boiling". Take a look here;
Do any of those look like what you saw? en.wikipedia.org...
:Clouds_edited.jpg This one currently sounds like what you're describing.
I'm not saying it is, I'm just saying that it is the closest comparison I can make with the words you've used. Further investigation into Wikipedia
also showed me this:
It's called Mammatus. I've never heard or seen it before, but it's definitely what I would call "boiling". The only thing is that this only
appears in conjunction with Cumulonimbus or Cumulus clouds - and I can't see it as "moving" that fast. Still, some verification if this is close to
what you saw would be useful.
Also of note, the Mammatus cloud is denoted as "Blue-ish Gray". Once again, this is where if the night was really night, or just late dusk is
important in uncovering the truth behind what you saw.
So yeah, sorry to sound like a skeptic, but I'd really like to verify that this is a real UFO story we're dealing with here. In either case however,
it sounds like you witnessed a rare event anyways! So stand tall and be proud at whatever answer comes out of this