What Causes These Unique Swirly Ice Formations?

[texasblitzem]

http://www.spaceweather.com/submissions/large_image_popup.php?image_name=Michael-French-swirlyICE_1296508078.jpg"

These are pretty cool looking. Any theories as to how they form backwards from the braided wire?

 

[pallidin]

No clue. Do you have any further info?

 

[cjl]

No idea why, but it does look like the spiral snow formation formed such that the snow spiral is perpendicular to the strands in the wires themselves. That could have something to do with it.

 

[Fish4Fun]

I vaguely remember a similar picture that made the newspaper back in the 70's. The article quoted some "physics expert" (likely a physics teacher @ a local high school) who stated the phenomena was related to the Coriolis effect. While I find this assertion implausible, I really cannot offer anything better. Generally ice does NOT form in such spirals, so it stands to reason that some special circumstances combined in both this case and the case from my youth. I do not live in an area where ice forms often, and so I have no first hand experience with how common this phenomena might be.

Very Cool Picture!

Fish

 

[Phrak]

Fascinating puzzle.

From the article:

"We also saw long "mohawks" of ice on the side of the telephone poles facing the wind, very much like rime ice."
​

This statement implies that ice should be deposited asymmetrically on the wire, as it did on the pole.

Then this statement:

"We assume the metal wires froze the nearly liquid snow, built up, and slide down the wire slowly due to gravity- forming beautiful swirly ice."​

Or maybe it was not just gravity but wind aided. An ice blob deposited on the wire could be unstable aerodynamically--any imbalance would push it left of right.

As the wire is stranded and spiral, gravity would resist winding in one direction, but not the other--if it could slide at all. If the blob slide slowly, spiraling down the wire, more ice would build-up asymmetrically to either side. (The leeward side?)

In the accompanying photo, note that the guy-wire angles downward away from the up wind direction. I would guess that this is probably a necessary condition, but I don't know why.

This partial explanation seems like it could make sense, filled-out, and under the right conditions, if two things (that I can think of) could be explained:

1) Why would the ice build-up slightly toward the top of the original blob so it forms a spiral rather than a disk, and then continue to do so?

2) Why would the ice, having first stuck to the wire, be able to form an interface layer that allowed it to creep down the guy-wire?

 

[texasblitzem]

"Indeed, the changing wavelength of the spiral suggests gravity played a role in their formation. This could be how heavy snow sags under its own weight when it clings to a braided wire. Why the spirals should oppose the braid, however, is not obvious.

READER FEEDBACK (CONTINUED): A popular suggestion was that Coriolis forces twisted the snow around the wire. This cannot be correct because the scale of the phenomenon is too small for a significant Coriolis effect. Likewise, water swirling down the drain of your shower is not guided by the Coriolis force; hurricanes, however, are.

Many readers noticed that the swirl of the snow was perpendicular to the underlying braid of the wire. This observation led to the most elegant explanation: "As the snow slides down, it will follow the twist of the wire, hence the spiral builds up with the opposite twist," said reader Jim Easterbrook. Another reader, Uwe Heine, added that "snow sliding down compresses the snow ahead of it. As the spirals 'pile up' the 'wavelength' of the spirals gets shorter, hence the shorter spirals near the ground." Many correspondents echoed these ideas.

Other ideas involving wind and the circular vibration of the guy wire had merit, too, but we will give the last word to reader Matt Kolasinski: "I think it was a bunch of snow sprites having some fun, building their own version of a luge run." Case closed."

This is on the Spaceweather.com home page. Someone should place a time lapse camera next to one to film its creation.

 

[Phrak]

This is on the Spaceweather.com home page. Someone should place a time lapse camera next to one to film its creation.

I think it takes some very uncommon conditions that, in all, would be difficult to discover, and then reproduce, or these helixis would not be noteworthy.