Icelandic volcano spawns searing, kilometre-high toxic twister
Tuesday, September 16, 2014, 8:49 AM - Bardarbunga, the volcano that's currently leaking lava and spewing sulphur dioxide gas into the air over Iceland, spawned something else of note recently - a towering vortex of heat and toxic gases that has been called a volcanado.
Video of the intensely-hot vortex was captured on Sept. 3, 2014, by NicAIR II, an infrared camera designed by Norway's Nicarnica Aviation to help aircraft pilots spot volcanic ash clouds while in flight.
A volcanado, very much like its 'cousin', the firenado, is similar to a tornado, but it has a different energy source. It can form in the same way as a tornado, as a horizontal rolling tube of air that's forced vertical due to updrafts, but again, the source of the updraft is different. For a tornado, the source is from above - the churning 'machine' of the storm cloud forcing air upwards inside the cloud and drawing it back downwards at the edges, and the bigger the storm, and thus the stronger those updrafts and downdrafts are, the more powerful the tornado can become. For a volcanado, the source is from below - the intense heat of the lava causes the air above it to rise rapidly, so any rolling tube of air that comes along can easily be forced vertical as it passes over the area.
Another way for a volcanado to form is simply from the turbulent eddies of air above the lava. As the super-heated air quickly rises, and air rushes in to fill the 'void' left behind, this causes the air to spin, and the more intense the heat, the faster that spinning becomes until it forms into a rapidly rotating column of hot air.
According to New Scientist, this volcanado reaches up to a kilometre above the ground, and while it isn't necessarily dangerous due to its wind speeds - as they probably only spin about as fast as a dust devil - there's far more to these vortexes than just the wind. As the video shows, the vortex is intensely hot, but if that's not enough of a reason to avoid it, you should probably know that it's toxic too. According to Fred Prata, the engineer who invented the camera that shot the images, "the tornado funnel is most likely filled with sulphur dioxide, gas and volcanic ash."
As an added note, volcanoes don't necessarily need to be spewing lava in order to spawn these spinning vortices. Pyroclastic flows - the incredibly dangerous blasts of gas and ash that some volcanoes emit, which can travel down the volcano's slopes at hundreds of kilometres per hour, can spin up numerous vortices in their wake, as shown in the video below.
Correction: The article originally stated that the volcano was producing ash as well as lava and sulphur dioxide gas. This was due to a misunderstanding of the Icelandic monitoring site, as they were reporting air pollution in units of micrograms per cubic meter, which is used for measuring particulate matter here in Canada. Thus, it was assumed that some of the air pollution was resulting from a small quantity of ash. However, the volcano is not currently producing ash. It is only releasing sulphur dioxide into the air, which is being measured in units of micrograms per cubic meter, rather than parts per billion (ppb).
(H/T New Scientist and Phil Plait for the story, and also to Facebook user Renée Arsenault Carter for pointing out the error)