Hi Paul,
Thank you for starting this interesting thread. I read through the article and, indeed, it is incredibly rare to see a comet, a thunderstorm and a fireworks display all happening at the same time. What luck this must've been!
I found these cool pictures online:
http://www.flickr.com/photos/rocksnhos/837466549/
http://www.flickr.com/photos/mortonphotographic/2640157354/
http://www.flickr.com/photos/ryandpaul/3453475467/
http://www.flickr.com/photos/silverhead/2463824166/
My personal favorite (cloud to ground strike):
http://forms.belointeractive.com/sharedcontent/datafiles/1152133558724 _ORIGINAL_FireworksLightning.jpg
Obviously, if lightning happens to be relatively closeby and especially if it is frequent or intense in nature, it is unsafe to hold a fireworks display, or to have any outdoor activity for that matter. As a general rule of thumb, so long as thunder is audible, you're always in danger of being struck. Speaking of lightning, we may see some good storm activity tomorrow (Thursday).
Thanks for sharing that awesome picture and site, Paul!
Trav.
