Sunday, November 8, 2009
Looking very much like water spouts, and often miss-named that way in many field reports in the past, these ‘plume twisters’, as I call them, are actually spinning columns of steam sucked out of the super-heated vortex of broiling plume steam.
As lava pours into the ocean the resulting collision produces all sorts of chemical and geological reactions such as sulfur dioxide, hydrochloric acid, ash, tephra, black sand, an assortment of glass particles, several other gases and lots of extremely hot steam. As the steam races rapidly upward the relatively colder water and air surrounding it tends to pull at the edges of the plumes rolling steam – stretching it out and producing these fingers and columns of spinning steam. There is no technical name for this phenomenon that applies exclusively to lava- generated plume steam. The closest proper descriptive is Steam Devil, or steam vortexes: “a rotating updraft that involves steam”.
Or maybe it is time we gave this unique phenomenon a local or Hawaiian name…. How about Niniu hawai ? In Hawaiian Niniu means ‘spinning, whirling’ and hawai means ‘steam, breath of water’…. Or maybe simply: Pele Devils :)
I have witnessed these steam vortexes separate from the plume and float off on the prevailing air currents, still rapidly rotating, and carrying on for a half-mile before dissipating into mist and disappearing. Below is a very unusual steam devil that separated off of the lava entry plume curving back onto itself to form a ring:
Posted by Leigh at 11:01 AM