The curious case of the snow structure in the nighttime

Last Sun., Feb. 12, everyone keeping score of impromptu, temporary constructions on Yale’s campus got to mark down something new and exciting in their notebooks: the arrival of the Cross Campus Igloo. Some might have speculated about the provenance of this Igloo. Was it related to the Igloo that popped up on Old Campus during the 2013 – 2014 school year? Who built it? Would it be totally dope to smoke a J in there, dude? It turns out the answers are (1) yes, (2) I’m about to tell you, and (3) duh (according to some intrepid snow explorers I talked to)! Read on to discover more about the newest addition to Yale’s winter wonderland.

To understand this igloo, we must understand the Original Igloo, situated for a brief stint three years ago on Old Campus. And to understand either, we must go all the way back to their mastermind: heavyweight crew team Social Captain John Risbergs, TC ’17. Risbergs, the Igloo’s “Ice Engineer,” is from Long Island presently but Latvia distantly—which is to say he is no stranger to snow. (Latvia, where it snows “six to seven months of the year,” according to Risbergs, could certainly give New Haven a run for its snow-money.) Risbergs first encountered igloo constructions in his childhood trips to Latvia. “It was a place where you could just dig into the snowfall and you’d have an igloo there,” he recalls. Many years later, as he sat cooped up in his Old Campus suite during a snowstorm, Risbergs decided to make an Igloo with some of his friends and teammates. It was a hit, as anyone who remembers the time of that first Igloo can attest. This time around, Risbergs decided to go bigger, and so construction began on the Cross Campus Igloo. The operation was professionalized: 12 to 13 members of the team worked on the igloo for seven hours total fromFriday night to Saturday evening, and the work was split into specialized roles.

In their research for the Igloo, the team discovered that igloos are traditionally built by stacking bricks ice of cut from the earth. Yale was a little short on the large ice formations, so they improvised: they packed normal, powdery snow into one blue recycling bin, put another recycling bin on top of it, and applied pressure, usually by jumping on it. This wasn’t a flawless process: according to Risbergs, “the first brick that [they] built fell completely apart.” Eventually, Angus Morrison, TD ’19, was installed as the “Brick Quality Control Officer,” and approximately 150-200 bricks were produced without incident.

On Friday night, the crew team was able to place three layers of bricks, though they didn’t cohere firmly. Risbergs felt some doubt at this point, but these doubts were dispelled when the construction crew’s return to the construction site Saturday after brunch revealed a sturdy, continuous structure. At this point, things got complicated. A team of two to three stood in the center of the igloo, receiving the bricks prepared by the separate recycling bin assembly line. They held each new brick in place while the Snow Packers and Water Throwers made sure it stuck. Finally, two bricks were joined together as a keystone for the arch. A little more packing and the job was done. Though the upper rings weren’t ideal—a little bit of a “spiral”—they were close enough. The Igloo was done.

There remained only turning it over to the public for whom they had built the Igloo. It was a great success. “You go in there and you see a box of Franzia, cans of beer… and you figure people are enjoying it at all times of the day,” Risbergs says.

II. A Mission, in the Dark of Night

“It was a mission. It was definitely a mission,” P.B. tells me in a hushed, isolated cranny of the Pierson College Common Room. He’s talking about his nighttime excursion last Saturday to the Cross Campus Igloo. He was on that most predictable of pilgrimages: hotboxing the igloo.

Dramatis Personae: The remnants of a party in the suite of J., P.B.’s friend. Approximately 12 attend the party; four make it to the igloo.

Motivation: Obvious—it’s totally cool to hotbox an igloo. Also, the same crew passed a J around and had a snowball fight last time it snowed, and they wanted something more low-key this time around. “J. was like, all right, everybody, mandatory: we’ve got to go [hotbox this igloo].”

Modus Operandi: One joint of cannabis, of mixed (and, as far as anyone remembers, unnamed) strains. Originally two Js, but someone bailed and kept one to smoke by herself in a perplexing “side sesh.”

The Scene: Surprisingly charming! P.B. was “expecting a shitty little ice cave,” but in the end the Igloo was “pretty legit.” The crumpled Budweiser cans, which P.B. described as part “chandelier” and part “shards of glass” stuck into the walls, made the space kind of “grimy,” but his impression was overall positive. And that means something, as P.B. is something of a connoisseur of icey smoke spots: he  frequents ski slopes which have similar snow caves built into the side of the mountain.

The hotbox crew hung out on a Cross Campus that was bustling with more activity than usual. It was half past midnight, but there were many spectators—some of whom “were like, ‘aww, shit, that’s awesome.’” The Igloo, it seems, was acting as a bona fide cultural hub. “I feel like the quads become much more social spaces in two situations,” P.B. says. “The first one being when it’s spring for the first time and it’s warm and there’s this nice grass to hang out at, and when it’s snow. So it was very much people gathering because of the snow.”

In an e-mail, J. described the hot box as a “stupefying success” and heartily encouraged me to do the same. (I did not, in fact, hot box the igloo.) The Igloo, he wrote, was for everyone, ranging from “once-a-week vaper[s]” to “casual toker[s]” and all the way up to “dedicated stoner[s].”

But what about those of us who are none of these things, but rather are concerned with contemplating the deeper mysteries of the Cross Campus Igloo? Who can deny the risk and thus the thrill, for example, of the hot box getting too hot and not boxy enough? In short: were our nighttime heroes at risk of melting the Igloo and causing a structural collapse? Just what is going on at the atomic level, anyway? Some of you STEM people might find this pretty basic, but I study Political Science and I think real science is just terrific. Let’s dive in!

III. Have Some Science

First, let’s consider the question above: were our hotboxers in danger of causing a collapse? It looks like they probably weren’t. According to Chris Wang, a PhD student in Physics, “it’s all about the rates: the rate of melting, and the rate of freezing.” Looking at an igloo, you might think that not much is happening with the ice—it is frozen, after all. Wrong! See, the bulk of the igloo consists of ice, which is the colloquial term for water molecules in a “mechanically stable” “crystal configuration.” But there’s a “very thin layer” on the surface of the ice where the material is constantly melting and refreezing. In order to weaken the Igloo structurally, our heterodox demolition crew would have had to cause the rate of melting at this very thin layer to exceed the rate of freezing and do so for many further layers. In the dead of night, this was unlikely—“a human body is not a huge source of heat,” Wang explained. Even during the day, they probably would have been in the clear, since the inner surface layer would be mostly insulated from the warming effects of the sun’s rays. But there’s a limit: an Igloo party is just like a normal party in that if it gets too crowded, the party will become too hot for comfort. (The difference is that most parties, unlike Igloo parties, don’t cause a ceiling collapse as a result of overheating.)

Also, it turns out that this Igloo was structurally pretty much perfect. Here’s a graph, prepared by Dr. Larry Wilen, Senior Research Scientist and Lecturer in Mechanical Engineering:

Contrary to popular belief, the perfect Igloo isn’t a half-sphere: it’s a catenoid, which—as you can see—is a near-perfect match with the shape of the Cross Campus Igloo. “If you have a hemispherical sort of cap, then you have… this tendency to push the walls out [at the bottom],” Wilen explained. The preferred height to diameter ratio for a catenoid structure starts at around 0.4, and the Cross Campus Igloo clocks in at a respectable 0.45. This structural robustness means that even as the ice “creeps”—acts, over long time-frames, analogously to a viscous liquid—the Igloo should be in good shape for a while. Wilen can’t predict how long it will last, but barring an increase in temperature, structural shocks (like someone jumping on the Igloo) or very thin walls, he thinks that the Igloo should remain relatively stable. “I was actually kind of amazed,” Wilen said of the Igloo’s structural robustness.

Unfortunately, this structural perfection meant a taller Igloo—otherwise, it would be too shallow and collapse—and it was the Igloo’s height which P.B. disliked the most. “It was like… okay, here’s this big dome that we can all stand under and happen to not be seen, but it didn’t feel like an igloo space,” he said. He would have liked it cozier. Still, they had a good time.

“It was very mellow,” P.B. told me. Which is good, but… was it maybe too mellow? The outing, which was designed as a stepping-stone to another party, was a “night ending event” for much of the crew. Undaunted, P.B. and one friend stumbled out of the smoky haze of the Igloo and made their way to Soggy Cigs.

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