Inward Tilting Icicles :: Part V :: French Curl

The following photo came through as the last photo in a French PowerPoint presentation of prize photography: Sur_le_vif.pps or Sur_le_vif.ppt. (If anybody finds it on a web site let me know) Not only is it beautiful, but it challenges our wisdom of last winter. Is this merely the result of gradual slipping? Is it differential freeze and melt? Postscript: Peter the spelunker notes: Stalactites can do this also in caves. Since they grow from the inside out, a blockage of the water channel or wind directions change can lead to those formations.

Inward Tilting Icicles :: Part IV :: Mass and Science

(a) See Gary Thomas' comment to Part III, noting serious academic research on bent icicles.

(b) Here is a contribution from Alan Gould, Dan Gould's brother. The shifting snow (and ice) mass theory. Some on-the-street verbal comments from friends have tilted in the same direction.

• ::

I have not been neglecting the icicle challenge. When I first saw the photos I thought "Hah, that's nothing. Take a gander at the attached photo that shows icicles that have twisted completely upside-down!" It was sent to me as a science puzzle---how did that happen? The photo is normal orientation with "down" towards the ground. Turns out the explanation that best fits is that the icicles formed on branches and as they formed the increased weight made the branch bend more and more until the icicle formed the weird J shape with part of it looking like it's totally upside-down. I wonder if the slanted icicles are not some similar effect, where they started forming on the edge of the piled up snow and when the weight of the icicle got to a certain point, perhaps combined with changing snow condition/temperature, caused the snow mass to shift and tilt the icicle as seen in the photo. Well there you have it.

• My definitive analysis.
• What do you think?
• ----Alan Gould

Inward Tilting Icicles :: Part III :: Trestle Shed Icicle

from: Dan Gould, Dec. 30.07, Fort Collins: Hi - Take a look at the photos. They were taken from the south side of the shed under the RR trestle on the Poudre Trail near the Highway 287 bridge. .

#1a indicates the location of #2 & 3.

. . . .

#2 is a close up taken from the east side.

. . .

#3 is a close up taken from the west side.

Ok - It must have to do with the amount of heating of the shed roof which is affected by the distance from the trestle. The amount of heating of the shed roof affects the flow of drops which determines if the ice grows on the cold side of the icicle. But which way the trestle affects shed heating and which way water drip drop rate affects icicle deviation - I need help on................... Thank you for the entertainment, Dan .. .. .. Note: Dan's photos do show that this is a highly selective phenomenon.

Inward Tilting Icicles :: Part II

Photo taken Monday Morning, December 17 about 9a.m.

Left photo taken Monday Morning, December 17 about 9a.m.; right photo about 12:30.

New facts, be they relevant or irrelevant.

Ambient went above freezing yesterday for several hours and is there again today.

The western tilting icicles came off before first inspection on the 16^th. (The orginal photo is from the 15^th.)

Note the short nearly vertical and round icicle at the front edge in today’s pictures. It formed yesterday.

Not visible in the picture: 2 tiny (about 3 inches “as we speak”) icicles are forming at the back of the pack,” and they are taking the characteristic inward slant of their big brothers.

The inward slanters have a definite fin shape—elongated east-to-west, or in the direction of slant. I would say the fin is more exaggerated today than yesterday, but I can’t prove it.

The distant photo for comparison with the 15th was taken about 9a.m. The left image in the closeup was also taken at that time. The right image was taken about 12:30. You can see in the distant pic the increase in inward slant from Friday to Sunday. There was also been a notable increase between 9 and 12:30 today, but I’m not sure my photos are convincing. You’ll have to believe me that the paddle of the wind chime is actually resting on the icicle in the later picture. Now, two hours later, the icicle has further invaded the chimes’ space.

Now for the conjectures and hypotheses that have come in by email and word. I’ll report in italic type what I have heard and add "quotes" to paste-ins from emails.

Honesty:

“I don't know.” (several responses)

Measured Skepticism:

“Optical illusion.”

“Your camera needs a regrinding of the lens.”

“Have you considered that the house is not plumb and the tilt is just an optical illusion? Would require that the door and porch be a trapezoid .. buy why not? ;-)”

Engineering:

The roof—the flat metal flashing at the edge is distorting under the edge. “The little roof actually pivots occasionally at the peak. The pivoting is caused by tremors, fickle breezes not affecting gutter icicles…” [Terribly boring, but quite reasonable. While this cannot be easily disproved, visual inspection yesterday revealed no obvious flex. Some flex is noted today but seems trivial even when allowing for the multiplier effect of the longer icicle relative to the overhang. The vertical icicle at the front seems to support this flex-explanation, but the the two little ones now forming on a slant behind seem to blow this explanation out of the 'ice.']

Tongue in Science and tongue in cheek:

Water coming over an edge tends, with surface tension to want to go inward after passing the edge and before dripping—so the icicle builds on its back side. “Melted water seeks the "inside" of the icicle when refreezing.” “surface tension aberration” [I like these simple explanations, but why don’t they apply to all icicles?]

“…this angle is caused by a combination of 1) surface tension between the flowing water molecules (they are charged) and the roof surface, and 2) the upward flow of air under the porch roof. Because of the loss of heat from your front door, the air is rising under this roof and this flow of air pulls the ice formation inward.”

“Melt water from the snow on the portico flows thru the snow, hits the roof, drains down the slope of the roof, reaches the icicle and flows down the inward side more often, freezing and building up that side preferentially.”

“The inside of the icicles are shaded from solar energy, so drops freeze there but not on the unshaded outside”

“Hmmmm dark door, warmer air, convection inward and upward as icicle freezes ?”

“… Wind swirling around the porch. Since the house faces south, a strong north wind would come down the roof, split on the gable over the porch and swirl on either side.”

“… Iron in the water. The presence of strong magnetic currents in the house, such as speakers or computer equipment could be pulling iron molecules inward.”

“ Each icicle is exerting gravitational pull on the other, thereby bringing them together.”

Head in ether:

“… or paranormal forces. I like paranormal forces.”

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Postscript:

About 6pm the postman arrived at the front door to deliver mail. He did that and also knocked down the tilted icicle. Here are the final photos: taken about 3pm this afternoon. Visibly more slanted. I hope you can see in the closeup the two little-and-slanted icicles forming at the rear. I must say, with the extent of the melting today, I expected it to soon choose its own moment of death.

Photos taken about 3pm December 17, 2007. . . .......... .......... ........... .................. ....... ......... .......... ........... ............. ......... ...........

Notice it was self-correcting toward vertical at the bottom.

Inward Tilting Icicles :: Part I; How?

You can see in the picture below the inward tilt of the icicles off the little roof over my front door. Nearby icicles hanging off the main roof are perfectly vertical. What's the physics of this phenomenon. I promise, if I knew I would say so. I have some theories, but I don't trust them. Can you explain it? Facts: the door faces south, and ambient temperatures have remained below freezing for a few days, so the melting is solar.