Mesocyclone or Mothership?

By Phil Plait

National Geographic Traveler just announced its winners for its 2014 photo contest. The shots are all very cool, but I can’t argue with the No. 1 pick: a mesocyclone over Colorado, taken by photographer Marko Korosec:

Holy wow! I love this shot. Korosec was storm-chasing on May 28, 2013, when this vortex appeared near Julesburg, Colorado, in the extreme northeastern corner of the state, near Nebraska. Despite what you might think, eastern Colorado is extremely flat, and prone to, um, interesting summer storms.

I’ve written about mesocyclones before (see Related Posts below for more jaw-dropping pictures and time-lapse animations). I can’t describe them much better than I did before:

A supercell is a rotating thundercloud; the spinning vortex in the middle is called a mesocyclone. Conditions need to be just so to create one. First you need a wind shear, where wind blows faster in one spot than another, so a blanket of air is flowing over another one. This sets up a rolling vortex, a horizontally rotating mass of air like the way a wave breaks when it gets to a beach. An updraft then lifts that vortex, which then spins vertically.

The warmer air in the vortex rises; this is called convection. If there’s a boundary layer of air above it, called a capping layer, it acts like a lid, preventing the vortex air from rising. It builds up power and can suddenly and explosively grow to a huge size. Wikipedia has a good description and diagrams of how this works.

Impressive. And what amazes me is that the photo above isn’t even what I think is the best one Korosec took of a mesocyclone. This one is:

WOW. It looks like a spaceship touching down, its thrusters disturbing the ground underneath it.

And just because I want to make sure you see it, here is a time-lapse of a supercell growing in Kansas, taken by Stephen Locke, because holy yikes it’s magnificent.

The next time someone tells me they’re feeling “under the weather,” they can be sure to get a lot of sympathy from me.

You can find more of Korosec’s photography—and it's all amazing, he’s really seriously gifted—at 500px, and on his website Weather-Photos.net.