Cumulonimbus Rising


I shared a beautiful lightning storm video by Kai Staats in my September 12, 2016 post, and it motivated me to try my own time-lapse video. What I'd like to capture is some towering cumulonimbus clouds building up over Phoenix. This often happens during our monsoon season. There wouldn't have to be any lightning, as the convective process that builds those clouds is itself fascinating to watch unfold.

So I've been waiting for the "perfect storm" of cumulonimbus, but a lot of things have to come together. The forecast has to be right, I need a clear view of it from my yard, where the weather needs to be clear and calm and safe to set up my camera. And of course it should be a grand display — not just a garden variety storm. That has yet to happen, and our monsoon season is now drawing to a close, so I'll share something I filmed a few years ago.

The video above was taken on July 13, 2013. It shows a "mediocre" display of cumulonimbus building up over Phoenix, AZ. The storm is centered over Mesa, which puts it at a distance of about 80 km (50 miles). The tops of those clouds are around 5000 meters (16,000 feet) altitude. Compare that to this cumulonimbus I captured as a still image during last year's monsoon season. Now that was a grand display. Alas, I wasn't set up for video that day.

FYI, my video isn't really a time-lapse. It's a real-time recording playing at 62X, compressing 28 minutes of time into a 27 second video. The recording was made with a Sony TVR310 Digital 8 camcorder, using a VCL-0637H wide angle 0.6X converter that provided a 75° FOV. All the digital processing was done in Adobe Premier.

I'll get something more dramatic at some point, but this is the best I have to date. Note that it does nicely show the formation of the "anvil" structure at the top of the storm cloud, and a lot of convective motion from the rising warm air. For more on the structure and formation of cumulonimbus clouds see my July 21, 2014 post.

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