Dust devil over water?

[M. Drabowski]

Is it possible? I just found some YT video showing apparently such phenomenon.
Or was it waterspout and people observing it just didn't realize that.
http://www.youtube.com/watch?v=_0uugP3pxOs

 

[rbstokes]

I cant watch it cause they block all that stuff in Afghanistan. However a dust devil is caused by intense surface heating. It will create a thermal gradient and the hottest air will rise quick causing other warm air to rush in and take its place. It starts to rotate and you have your dust devil. You can usually walk out here in the summer and at almost any time see dust devils.

 

[Greg Stumpf]

I've seen decent dust devils move over a body of water and continue to spin, but they never look that strong. In this case, one wonders what was over their heads. That looks almost looks like a weak waterspout.

 

[David E. Young]

It looks like a dust devil-like vortex over water. Sort of reminds me of the "Hay Devil" vortex from Tom Grazulis' video series, if you remember.... a vortex in a non-desert area that is invisible except for what it does in contact with the ground. Most likely the same air physics as a dust devil.

 

[Jeff Snyder]

There isn't really one singular "cause" of dust devils, since the term "dust devil" is often used to describe any surface vortex (that's usually relatively shallow) that isn't associated with a thunderstorm or storm outflow (that is, isn't a tornado or gustnado). In the textbook case, dust devils are associated with superadiabatic lapse rates near the surface/land. In the Plains, dust devils are pretty common on hot days when the winds are relatively weak, though you can also have a vortex that looks very similar when the winds are stronger too. I'd be surprised to see superadiabatic lapse rates over water since much of the incoming solar radiation that hits a lake, for example, will be "used" to evaporate water, with less sensible heating. This is in contrast to a field with dry soil, in which incoming solar radiation largely results in sensible and ground heating since there's little latent heating that can occur; the sun's "energy" is used to warm the ground and the air immediately above the ground, since there's very little water to evaporate.

In the case of the video above, it sounds occasionally like it was windy. If that was the case, then perhaps this could have been an eddy that developed downstream of a break in the trees or some other structure. I'm sure we've all walked out of a store or other large building to see a vortex tossing leaves or garbage. If the winds were relatively strong, a vortex may have spun up along or downwind of the edge of a grove of trees (or, really, anything that can "block" or significantly slow the wind). The horizontal gradient in the wind creates vertical vorticity (or, rather, is associated with vertical vorticity), which may wrap up into a vortex.

 

[Tony Lehman]

That was an interesting video clip. I have seen whirlwinds move out over water before, but that was a large one.

I am just an amateur observer but I have a couple of thoughts to share. Back when I was a boy and out bank fishing at a lake, I heard a wind coming through the trees behind me and a rustling noise in the leaves. I looked around to see a whirlwind (dust devil) spinning up a column of leaves and ground litter. It moved down the hill and moved out over the water close to me. It ruffened up the water same as the video and right at the center, it sucked up a small inverted cone of water several inches high. And the water droplets and spray were slinging outward from the tip of the cone.

Later years when I had a light plane and often flew around for pleasure, I would occasionally search for dust devils. At certain times of the year they were plentiful and could be seen from the air easily. You could see them track across the ground. And once I followed one out over a big lake. It did not dissipate, but left a wake like a boat would. Also, I know I flew through one once as the light plane suddenly yawed vigorously one direction, then the other. I never saw anything in the air. I think these things get their power when a parcel peals away from the ground and lifts vigorously aloft to thousands of feet.

 

[Stephen Levine]

Thank you for the awesome link. I noticed that it became a Multivortex" dust devil as well, which is quite unusual.

 

[Bernard Hulshof]

Great video!
Last year there was a similar "water vortex" over a lake near Amsterdam, the Netherlands. It was nearly powerful enough to blow over a rubber boat :
http://www.youtube.com/watch?v=iDsc3QtK2Dw