Interesting Cloud Formations

Late summer has been rather boring around northern Illinois on the weather front. However, a few interesting cloudscapes have meandered across our region. Below are a couple cases illustrated by stills; I'll have another post soon illustrating unique time-lapse movies captured from the Department of Geography's webcam system.

The first set of pictures are illustrative of hole-punch cloud formations that traversed the area on 7/30/2012. I only caught the tail-end of this unique display as I was in the midst of a six mile run with no camera during the height of it.  Luckily, NIU photographer friend, Rodney Neace, was able to capture the beautiful hole-punch formations in their full glory with his iPhone. Hole-punch clouds are a great illustration of a localized human-induced weather modification. Essentially, private and/or commercial aircraft can "seed" the cloud deck, promoting an ensuing hole-punch or trough, as well as fall-streak. A detailed manuscript on these features was published in BAMS in 2010. Below are Rodney's pics, as well as  few of my own.

For those Deadheads out there -- doesn't this look like a Steal Your Face skull? 

Three mature hole-punch formations, as well as a trough, producing a smiley face. This feature was much more definitive about 15 minutes before this shot -- argh! always carry a camera!

The second interesting cloud formation was ahead of a rather unimpressive MCS that moved across the region during the early morning hours of 8/16/2012. I was in the DeKalb wind farm region trying to time-lapse a shelf (which never really materialized) when I noticed unique horizontal vortices embedded within the altostratus ahead of the line. These features only lasted about 3-4 minutes before they kinked up and dissipated. I don't think I've ever seen such a formation documented before ... and I'm truly baffled by their cause.