Snow Science Against the Avalanche

对抗雪崩的雪科学

On slopes shallow enough to accumulate snow but steep enough for it to be unstable, chaos hides beneath the surface.

在浅到足以积雪，但陡到足以导致不稳定的山坡上，混乱就隐藏在表面之下。

One night earlier this winter, the only road out of Alta, Utah, was closed down. At ski lodges, signs warned guests to stay inside or face fines. Already that season, twenty-two feet of snow had fallen, and, the day before, a storm had dropped thirty-three inches; another foot was predicted by morning. The most dangerous time for avalanches is after a rapid snowfall, and three-quarters of the buildings in Alta are threatened by a known avalanche path. A standard measure for danger on roads, the Avalanche Hazard Index, computes risk according to the size and frequency of avalanches and the number of vehicles that are exposed to them. An A.H.I. of 10 is considered moderate; at 40, the road requires the attention of a full-time avalanche forecaster. State Highway 210, which runs down the mountain to Salt Lake City, if left unprotected, would have an A.H.I. of 1,045.

今年冬天早些时候的一个晚上，离开犹他州阿尔塔市的唯一道路被关闭了。在滑雪旅馆，告示牌警告客人留在室内，否则将面临罚款。那个季节已经下了22英尺的雪，而在前一天，一场风暴就降下了33英寸的雪；预计到早上还会有1英尺。发生雪崩的最危险时刻是在快速降雪之后，阿尔塔有四分之三的建筑受到已知雪崩路径的威胁。一个衡量道路危险性的标准——雪崩危险指数就是根据雪崩的大小和频率以及暴露在雪崩中的车辆数量来计算风险。雪崩危险指数为10时被认为是中等水平；达到40时，该道路就需要全职雪崩预报员的关注。而从山上延申到盐湖城210号州际公路如果不加保护，其雪崩危险指数将达到1045。

Just before 5 a.m., a small group of ski patrollers gathered at a base by the resort’s main lift. Dave Richards, the head of Alta’s avalanche program, sat in the control room. Maps and marked-up aerial photographs hung on the wall next to what looked like a large EKG—that season’s snowfall, wind speeds, and temperature data plotted by hand. Clipboards on hooks were filled with accounts of past avalanches.

就在早上5点之前，一小群滑雪巡逻员聚集在度假村主缆车旁的基地中。阿尔塔雪崩项目的负责人戴夫·理查兹坐在控制室里。墙上挂着地图和标满注释的航空照片，旁边是一幅巨大的图表——那一季的降雪量、风速和温度数据是用手绘制的。挂在钩子上的剪贴板上则写满了过去雪崩的记录。

Forty and bearded, with tattoos on his arms, Richards has the bearing of a Special Forces soldier. He wore a vest with a radio strapped to it and held a tin of dipping tobacco, spitting occasionally into the garbage can beneath his desk. He obxts when people say that he works in avalanche control; he prefers the term “mitigation.” Sitting nearby was Jude, his English cream golden retriever, named for the patron saint of lost causes.

理查兹四十岁，他满脸胡须，手臂上有纹身，有一种特种部队士兵的气质。他穿着一件背心，上面绑着一台收音机，拿着一罐浸渍烟草，偶尔向办公桌下的垃圾桶吐口水。当人们说他从事雪崩控制工作时，他表示反对；他更喜欢用“缓解”一词。坐在附近的是裘德，他的英国奶油金毛猎犬以迷途者的守护神命名。

Jonathan Morgan, the lead avalanche forecaster for the day, described the snow. He wore a flat-brimmed cap and a hoodie. “Propagation propensity’s a question mark,” he said. “Not a lot of body in the slab. . . . Dry facets, two to three mils,” he continued. “It’s running the whole gamut of crystal types—wasn’t ice, by any means. Rimy, small grains.”

当天的首席雪崩预报员乔纳森·摩根描述了这场雪。他戴着一顶平边帽，穿着一件连帽衫。“裂缝的扩展倾向还是一个问号”，他说，“板块中没有很多雪体……干燥面长达两到三英里。”他继续说道：“它包括了所有的晶体类型——但无论如何，它都不是冰。它的外面有一层白霜，呈现为小颗粒状。”

At ski resorts like Alta, large avalanches are avoided by setting off smaller ones with bombs. On the walls above the maps were dummy mortar rounds. Above Richards’s desk were binders marked “Old Explosives Inventory.” The idea, Morgan explained, was to “shoot the terrain we can’t get to.”

在阿尔塔这样的滑雪胜地，大型雪崩是通过用炸弹引爆小型雪崩来加以避免的。在地图上方的墙上挂着仿制的迫击炮弹。在理查兹的办公桌上方有标有“旧爆炸物清单”的夹子。摩根解释说，这个想法是为了“射击我们无法到达的地形”。

Richards started considering their targeting plan. The ski resort is cleared from the top down: first by artillery shells, then with hand charges. Before any shots are fired, paths leading to the mountains are closed. Because not all skiers keep to groomed trails—backcountry adventurers seek out remote areas—the Utah Department of Transportation also checks the roadside for tracks. Sometimes it scours the mountainside with infrared cameras before giving the all-clear.

理查兹开始考虑他们的目标定位计划。滑雪场是自上而下清理的：首先是炮弹，然后是手榴弹。在发射任何炮弹之前，通往山上的道路都将被关闭。因为不是所有的滑雪者都坚持走梳理过的小路——越野冒险家们会寻找偏远地区——犹他州交通局也会检查路边的痕迹。有时，在批准之前，它还会用红外线摄像机在山坡上进行搜索。

“So we’ll go fourteen for Baldy?” Richards said. “Doesn’t include a shot seventeen.” Baldy was one of the resort’s mountain faces, at which they planned to fire fourteen shells; seventeen was a spot on its ridgeline.
“Seventeen wouldn’t be the worst idea,” Morgan concurred. “You got a seven in there?”
“When was Baldy shot last?” Richards asked. “Forty inches ago?”
“Yeah, Friday morning.”

“那么，我们将从秃子坡继续向前十四步？”理查兹说，“不包括17号点。”秃子坡是度假村的一个山坡，他们计划向其发射14枚炮弹；17号点是其山脊线上的一个点。
“17号点并不算最糟糕的主意，”摩根同意，“你要向那里发射7枚炮弹？”
“秃子坡最后一次被射击是什么时候？”理查兹问道：“是积雪厚度40英寸以前？”
“是的，在星期五早上。”

Richards and Morgan repaired to the mess hall—dark carpet, pool table, a deer head on the wall—for breakfast. At five-thirty, the ski lift opened. As Richards walked out the door, Liz Rocco, another ski patroller, mentioned that she had prepared some of the hand charges they would be using that morning. “And I will light them, and throw them into the darkness,” Richards said.

理查兹和摩根回到了食堂——这里有黑暗的地毯、台球桌、墙上的鹿头——吃早餐。五点半的时候，滑雪缆车开动了。当理查兹走出门时，另一位滑雪巡逻员丽兹·罗科提到，她已经准备好了一些他们那天早上要用的手榴弹。“我将点燃它们，并把它们扔进黑暗中，”理查兹说。

We rode the lift up in the moonlight. Snow was falling on the fir trees. Richards spent his childhood at Alta: his father was a ski patroller for thirty-three years, and his mother, who later became a university administrator, worked the front desk at the Rustler Lodge. Richards started his career as a professional skier, then worked as a heli-skiing guide, before joining the patrol full time. “The thing that makes it for me is the snow,” he said. “Working with a natural material that can be—” He paused. “It’s light and fluffy and soft and downy, and it’s everybody’s favorite thing in the world. It’s also one of the most destructive forces in nature. Under the right conditions, that soft, wonderful little snowflake can tear forests out of the ground, throw cars through the air, flatten buildings. And you get to watch that.”

我们在月光下乘坐电梯上去。雪落在冷杉树上。理查兹在阿尔塔度过了他的童年：他的父亲在滑雪场当了33年的巡逻员，他的母亲后来成为一名大学管理人员，在拉斯特尔旅馆的前台工作。理查兹以职业滑雪者的身份开始了他的职业生涯，然后担任直升机滑雪向导，最后全职加入巡逻队。他说：“对我来说，最重要的事情是雪。”“与一种天然材料一起工作，可以…… ”他停顿了一下，“它轻盈、蓬松、柔软、有绒毛，它是世界上所有人最喜欢的东西。它也是自然界中最具破坏性的力量之一。在适当的条件下，这种柔软、美妙的小雪花可以把森林从地面上撕下来，把汽车抛向空中，把建筑物压平。而你可以看到这些。”

At the top of the lift, we started hiking. A voice crackled over the radio. “Copy,” Richards said. “Just give me a holler when you pull the trigger.” A moment later, the radio crackled again; Richards ducked and covered his head, and an explosion went off somewhere nearby. We resumed hiking. After a few minutes, we arrived at a two-story shed. A garage door opened onto a pair of hundred-and-five-millimetre howitzer cannons, of Second World War vintage, installed on semicircular tracks. The gun barrels were pointed at the mountaintops. A crew was loading bags of gunpowder into the undersides of artillery shells—enormous bullets, six inches wide and two and a half feet long. Richards wrapped a rag around a large stick and jammed it into a gun barrel, to clean it. “One Sunday morning,” he began singing to himself. “As I went walking . . .”

在电梯的顶部，我们开始徒步旅行。一个声音在无线电中噼里啪啦地响起。“收到，”理查兹说道，“当你扣动扳机时，吱一声。” 一会儿，无线电又响了起来；理查兹躲了起来，捂住了头，附近某个地方发生了爆炸。我们重新开始了徒步旅行。几分钟后，我们来到了一个两层楼的棚子。一扇车库的门打开了，里面有一对一百零五毫米的榴弹炮，它们是第二次世界大战的产物，安装在半圆形的轨道上。炮管对准了山顶。一名工作人员正在将一袋袋火药装入炮弹的底部——巨大的炮弹宽六英寸，长两英尺半。理查兹将一块抹布缠在一根大棍子上，塞进一根炮管来清洁它。“一个星期天的早晨，”他开始对自己唱歌，“当我走在路上……”
原创翻译：龙腾网 http://www.ltaaa.cn 转载请注明出处


The patrollers donned foam earplugs and large over-ear headphones; Richards and his co-gunner walked around one of the weapons, checking locks and bolts. They turned a crank, and the barrel swung toward its first target.
“Zero, zero, two, seven,” Richards yelled—the elevation and the deflection. Two other patrollers confirmed the coördinates. “Ready to fire,” Richards said. “Fire!”
He pulled hard on a chain. The muzzle flashed, and a plume of acrid smoke filled the air. There was a high-pitched ringing.

巡逻人员戴上了泡沫耳塞和大型耳罩式耳机；理查兹和他的副炮手绕着其中一件武器走了一圈，检查锁和螺栓。他们转动一个曲柄，炮管向第一个目标摆动。
“零，零，二，七，”理查兹大喊——这是仰角和偏转度。另外两名巡逻员确认了这一坐标。“准备开火，”理查兹喊道：“开火！”
他用力拉动一条铁链。炮口一闪，一缕刺鼻的烟雾弥漫在空气中，发出了一阵高亢的响声。

It wasn’t possible to see the mountain, but Richards listened for impact and, a few seconds later, yelled, “Report!” Outside, while the barrage continued, a patroller named Kyle took a small cast-booster explosive out of his pack: it resembled two cans of beans wired together with licorice, the cartoon version of a bomb. He pulled the fuse and tossed it underhand over the cliffside. “That didn’t go where I wanted,” he said. Ninety seconds later, it exploded into a black-and-white cloud of snow dust.

那座山是无法看到的，但理查兹听着了中弹声，几秒钟后，他大喊：“报告！”在外面，当炮击继续进行时，一个名叫凯尔的巡逻员从他的背包里拿出了一个小型助推炸药：它就像两个豆子罐头用甘草连在一起，是一种卡通版的炸弹。他拉开导火线，暗中把它扔到了悬崖边上。他说：“这不是我想要的结果”。90秒后，它爆炸了，变成一团黑白相间的雪尘。

Afterward, the cleaning and stowing of the guns began. When everything was done, it was nearly nine o’clock. Richards prepared to ski back toward the base. During the night, the resort had sent an alx to Alta skiers, telling them to expect between nine and fourteen inches of new snow—some of the best skiing of the season. On the way down, the sun shone on fresh powder reaching up to Richards’s waist. Small cracks shot out from his ski tips as he descended. Piles of snow slid downslope. He paused and, turning his ski pole upside down, began using it as a probe. The pole slid easily into the first foot of snow. Feeling resistance, he pushed harder—and broke through into a hollow. After the snow settled and drifted, there could be avalanches.

之后，他们开始清洗和收放枪支。当一切完成后，已近九点。理查兹准备滑回基地。夜里，度假村向阿尔塔的滑雪者发出警报，告诉他们预计会有9至14英寸的新降雪——这可以算是本季最好的滑雪机会之一了。在下山的路上，阳光照耀着新鲜的雪粉，它直达理查兹的腰部。当他下山时，小裂缝从他的滑雪尖上射出。一堆堆的雪从斜坡上滑落下来。他停了下来，把他的滑雪杆倒过来，开始把它当作一个探测器。滑雪杆轻松地插入第一英尺的雪地。感觉到阻力后，他更加用力——冲进了一个空洞。在雪沉淀和漂移之后，可能会出现雪崩。
原创翻译：龙腾网 http://www.ltaaa.cn 转载请注明出处


The project of avalanche control in the Alps goes back at least to 1397, in Andermatt, Switzerland, with a law that prohibited logging. Swiss peasants had moved farther into the mountains. Their new farmhouses sat in avalanche paths. It was soon discovered that old-growth trees anchored the snow and kept slides from gathering mass. During the eighteen-seventies, Johann Coaz, the head of the Swiss Forest Service, made records of historical avalanches. He drew up maps of potential disaster zones and designed walls to protect vulnerable settlements; the stones used to build them were hauled up the mountainsides by hundreds of men.

阿尔卑斯山的雪崩控制项目至少可以追溯到1397年，在瑞士的安德马特，有一项禁止伐木的法律。瑞士农民已经搬到了更远的山里。他们的新农舍坐落在雪崩的道路上。人们很快发现，古老的树木可以固定住雪，使滑坡不至于聚集成一团。十八世纪七十年代，瑞士林业局局长约翰·科兹对历史上的雪崩进行了记录。他绘制了潜在灾害区的地图，并设计了保护脆弱居民点的墙壁；用于建造墙壁的石头由数百人拖到山坡上。

Around the same time, prospectors in the western United States began finding silver ore high in the mountains. At Alta, which began as a major silver camp, miners logged the alpine forests for firewood and to reinforce their tunnels. According to legend, the avalanche danger grew so high that women weren’t allowed to live there in winter. Alta was abandoned in 1927, when the price of silver plummeted, but, in the nineteen-thirties, European-style ski resorts spread across the American West. The first mechanical lift appeared in Alta in 1939.

大约在同一时间，美国西部的勘探者开始在高山上发现银矿。在阿尔塔，最初建造的一个大型的银矿营地，矿工们砍伐高山森林作为木柴并加固他们的隧道。据传说，雪崩的危险性越来越高，以至于妇女在冬天不被允许住在那里。阿尔塔在1927年银价暴跌时遭到了遗弃，但在1930年代，欧洲风格的滑雪胜地遍布美国西部。1939年，阿尔塔出现了第一条机械索道。

After the Second World War, some veterans of the U.S. 10th Mountain Division, who had trained for alpine combat, found themselves responsible for snow safety at the resorts. In 1945, Montgomery Atwater, a freelance writer who had fought with the 10th, heard about a snow-ranger job at Alta and applied on a whim. “That Alta was ideally conceived by nature to become the first avalanche research center on this continent and that I was there to take the plunge were mere coincidences,” he later wrote, in “The Avalanche Hunters,” from 1968.

第二次世界大战后，美国第十山地师的一些退伍军人——他们曾接受过高山作战的训练——开始负责度假区的雪地安全。1945年，曾在第10师战斗过的自由作家蒙哥马利·阿特沃特听说阿尔塔有一份雪地巡视员的工作，一时兴起就去申请了。他后来在1968年的《雪崩猎人》中写道：“阿尔塔被大自然完美地构想为这个大陆上的第一个雪崩研究中心，而我在那里决定冒险一试，这只是巧合而已。”

Alta lies at the center of three storm tracks, from Canada, the Gulf of Alaska, and the Pacific. Storm systems accumulate moisture in the Salt Lake and, as they rise into the mountains, release about forty-five feet of snow each winter. Atwater learned that although snow always begins the same way—with a water droplet condensing around a dust mote or pollen to form a six-pointed snowflake—it can take innumerable forms later. Snow acts like both a solid and a liquid: it flows—even a blanket of snow on a hillside is slowly creeping—while maintaining its structure. Scientists consider it to be “warm,” because it is always close to its melting point. This is why, before you make your first snowball of the day, it is hard to know how well it will pack: you are working with a material that is about to change state. It’s like building a bridge with red-hot steel.

阿尔塔位于三个风暴路径的中心，它们分别来自加拿大、阿拉斯加湾和太平洋。风暴系统在盐湖中积累水分，当它们上升到山区时，每年冬天会释放出大约45英尺的雪。阿特沃特了解到，尽管雪总是以同样的方式开始——水滴在尘埃或花粉周围凝结，形成六角形的雪花——但之后却可以采取无数的形式。雪的行为既像固体又像液体：它在流动——甚至山坡上的一片雪毯也在缓慢地蠕动——同时保持其结构。科学家认为它是“温暖的”，因为它总是接近其熔点。这就是为什么在你做今天的第一个雪球之前，你很难知道它的包裹效果如何：你正在处理一种即将改变状态的材料。这就如同用烧红的钢建造一座桥。

We think of the snow on a mountain as a solid mass. In reality, it is a layer cake created by serial snowfalls, each layer distinctive and changeable. “The snow cover is never in a state of repose,” Atwater wrote. “It is continually being pushed, pulled, pressed, bent, warmed, chilled, ventilated, churned.” The topmost layer might be evaporating into the night air; at the same time, radiant heat from the ground, or from nearby trees, could be melting the lowest layer. When the temperature differences between the layers are small, snow tends to sinter, or coalesce: the crystals knock off one another’s arms, becoming rounded grains that fuse into a strong, dense snowpack. When the differences are larger—say, between the pack and the ground—snow vaporizes upward and refreezes, creating hollow, cup-shaped crystals. The result is brittle, spiky snow, called depth hoar. (In ice cream, a similar process creates freezer burn.)

我们认为山上的雪是一个固体块。实际上，它是一个由连续降雪形成的层状蛋糕，每一层都是独特的、可改变的。阿特沃特写道：“雪层从未处于静止状态，它不断地被推、被拉、被压、被弯曲、被加热、被冷却、被通风、被搅动。”最上面的一层可能正在蒸发到夜晚的空气中；同时，来自地面或附近树木的辐射热可能正在融化最底下的一层。当各层之间的温差较小时，雪往往会熔结，或凝聚在一起：晶体相互撞击，成为圆形的颗粒，融合成一个坚固、密集的雪堆。当温差较大时，例如，在雪块和地面之间，雪向上蒸发并重新冻结，形成空心的杯状晶体。其结果是脆性的、带刺的雪，被称为深度囤积物。(在冰激凌中，一个类似的过程产生了冰柜冻烧）。

Neither settled snow nor weak hoar is dangerous in itself. The problem arises when a dense layer lies atop a weak layer to which it is poorly bonded. Depth hoar is “the eeriest stuff on any mountain,” Atwater wrote; it grows unseen, rotting the snow until it is weak and potted. It is strong in compression but weak in shear. Like a row of champagne glasses slowly loaded with bricks, it can hold a surprising amount of weight until, with the slightest shove, the structure falls apart, creating a slab avalanche.

无论是稳定的雪还是脆弱的白霜，其本身都不危险。当一个密集的雪层位于一个脆弱的雪层之上时，问题就出现了，因为两者之间结合得很差。深层积雪是“所有山峦上最可怕的东西”，阿特沃特写道；它在不为人知的情况下生长，破坏雪，直到它变得脆弱和腐烂。它在压缩方面韧性强大，但在剪切方面却很弱。就像一排香槟酒杯慢慢地装上砖头一样，它可以承受惊人的重量，直到在最轻微的推力下，结构分崩离析，形成板状雪崩。

The word “avalanche” is too graceful for the phenomenon it describes. On slopes shallow enough to accumulate snow but steep enough for it to be unstable—the sweet spot is said to be thirty-nine degrees—the layers will separate, and the slab will crack and slide. Churning violently, the snow reaches eighty miles per hour within a few seconds. A skier who avoids colliding with trees and rocks is likely to be pulled under, then pinned in place by thousands of pounds of snow that harden like concrete. Very few people can dig themselves out; most can’t even move their fingers. Within minutes, an ice mask forms around your face. You asphyxiate on your own exhaled carbon dioxide.

“雪崩”这个词对于它所描述的现象来说太过优雅了。积雪在足够浅的斜坡上，但它又足够陡峭，使雪不稳定——据说最有效的坡度是39度——雪层会分离，板块会开裂和滑动。在激烈的搅动下，雪在几秒钟内达到每小时80英里的速度。一个避免与树木和岩石相撞的滑雪者很可能被它赶上，然后被数千磅像混凝土一样变硬的雪钉在原地。很少有人能把自己挖出来；大多数人甚至不能移动他们的手指。在几分钟内，你的脸就会形成一个冰罩。你会因为自己呼出的二氧化碳窒息而死。

At a test site in the mountains, Swiss scientists have set off avalanches powerful enough to destroy their equipment. Photograph by Yann Gross

在山区的一个试验场，瑞士科学家引发了足以摧毁其设备的雪崩。
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In his book “Staying Alive in Avalanche Terrain,” from 2008, Bruce Tremper, the former director of Utah’s Avalanche Center, offers a taxonomy of avalanches. In slab avalanches—the most dangerous kind—an entire layer releases at once. In storm slabs or wind slabs, the releasing layer falls from above; in wet slabs, a layer lower down is weakened by water; in a persistent slab, it was weak to begin with. A soft slab, composed of powdery snow, tends to break where you stand; a hard slab breaks above you, which is more perilous. Non-slab avalanches are said to be “loose.” In a dry loose avalanche, powder releases in disconnected sloughs. Wet loose avalanches—portended by “pinwheels,” small snowballs that leave streaks as they roll—are slower but stickier, and more likely to bury you if you get caught. Mixed avalanches, which start dry and get wet lower on the slope, have become increasingly common. So have glide avalanches, caused by meltwater seeping in below the snowpack.

犹他州雪崩中心前主任布鲁斯·特伦普在其2008年出版的《在雪崩地带生存》一书中提供了雪崩的分类法。在板状雪崩（最危险的一种雪崩）中，整个雪崩层一次性被释放出来。在风暴雪崩或风雪崩中，释放层从上面落下；在湿雪崩中，较低的一层雪被水削弱；在持续的雪崩中，它一开始就很脆弱。由粉状雪组成的软雪层往往在你站立的地方断裂；硬雪层在你上方断裂，这就更危险了。非板状雪崩被说成是“松散的”雪崩。在干燥的松散雪崩中，粉末以断开的槽状释放出来。湿的松散雪崩——其预兆是“针轮”，即滚动时留下条纹的小雪球构成——速度较慢，但更粘稠，如果你被卷入，它更有可能将你埋葬。混合雪崩——它开始时是干的，在坡度较低的地方变湿——已经变得越来越普遍。滑动雪崩也是如此，它是由雪堆下面的融水渗入造成的。

Students of tsunamis or volcanoes must wait for nature to deliver their disasters, but an avalanche can be provoked. In the nineteen-fifties, Atwater used a technique now called “ski-cutting.” Two patrollers descended dangerous slopes; while one looked on, ready to stage a rescue, the other skied to a safe point on the far side, picking up enough speed to try and ride through any avalanches he might start. In theory, the slopes that slid were safer because of it; the ones that didn’t were deemed stable enough for everyone else.

研究海啸或火山的学生必须等待大自然给他们带来灾难，但雪崩是可以被引发的。在1950年，阿特沃特使用了一种现在称为“滑雪切割”的技术。两名巡逻员从危险的山坡上下来；当一名巡逻员看着，准备进行救援时，另一名巡逻员则滑到远处的一个安全点，提高足够的速度，试图穿越他可能引发的任何雪崩。从理论上讲，滑落的斜坡因此更安全；没有滑落的斜坡对其他人来说也被认为足够稳定。

It wasn’t practical to ski-cut every hill. Knowing that the Swiss used bombs to combat avalanches, Atwater tapped the Forest Service’s wartime supply of tetrytol, the high-powered explosive; he asked his supervisor whether he could have some artillery, for distant targets. National Guardsmen arrived with a First World War-era French 75. (“What would avalanche research be without war surplus?” he later wrote.) For mid-range targets, too close for artillery but too distant for hiking or skiing, Atwater tried rifle grenades, bazookas, bombs dropped from helicopters, and an air-to-air rocket known as the Mighty Mouse. These methods were too costly, or unsuited to the snow; in the end, a modified ball machine, of the sort used for batting practice, was the most reliable delivery mechanism. Richards’s team still uses Atwater’s “Avalauncher” to shoot about thirty rounds each morning.

对每个山头进行滑雪切割并不切合实际。阿特沃特知道瑞士人用炸弹来对付雪崩，于是他动用了林务局战时供应的“三氧化二氮”，即高能炸药；他询问其上司，他是否可以得到一些炮弹，用于轰击远处的目标。国民警卫队的人带着第一次世界大战时期的法国75型大炮来到了这里。（他后来写道：“如果没有战争遗留物，雪崩研究会是什么样子？”）中距离目标对火炮来说太近，但对徒步旅行或滑雪来说又太远，阿特沃特尝试了枪榴弹、火箭筒、从直升机上投下的炸弹，以及一种被称为“大老鼠”的空对空火箭。这些方法成本太高，或者不适合在雪地上使用；最后，一个改良的发球机，即用于击球练习的那种机器，成为了最可靠的投掷器械。理查兹的团队仍然使用阿特沃特的“雪崩机”，每天早上发射大约30发子弹。

Atwater worked with Ed LaChapelle, who had done a stint at the Swiss Avalanche Institute, to create a “snow study plot”—a clearing where they could measure snowfall and take samples of the snowpack at regular intervals. They tracked the snow’s rate of accumulation and weight in water, discovering that weight mattered far more than depth: when placed atop a layer of hoar, a foot of fluffy powder was less dangerous than three inches of dense slush. Wind, they learned, could deposit many feet in just a few hours; pillows of windblown snow looked tranquil but were deadly. Studying how snow settled, Atwater wrote, “We saw things going on within that placid-appearing mass which no man had seen before—or even suspected.” He concluded, “There are apparently random plastic flows and currents within the snow cover whose causes and effects were unknown, and still are.”

阿特沃特与曾在瑞士雪崩研究所工作过的埃德·拉夏贝尔合作，创建了一个“雪地研究区”——一个他们可以测量降雪量并定期采集雪堆样本的空地。他们跟踪了雪的积累速度和水的重量，发现重量比深度重要得多：当放置在一层白霜上时，一英尺的蓬松粉末比三英寸的稠密泥浆更危险。他们了解到，风可以在短短几个小时内存积许多英尺的雪；被风吹起的雪枕看起来很平静，但却是致命的。阿特沃特在研究雪是如何沉积的时候写道：“我们看到在这块看似平静的土地上发生的事情，以前没有人看到过，甚至没有人怀疑过。”他总结说：“在雪层中显然存在着随机的塑性形变和流动，其原因和影响不为人知，现在也是如此。”

In 1805, the Irish hydrographer Sir Francis Beaufort developed a scale for measuring wind speed at sea by observation. Later, it was adapted for use on land. In his book “Defining the Wind,” from 2004, Scott Huler argues that the descxtions accompanying the scale, which were written anonymously, should count as literature. At Beaufort 0, the wind is “calm; smoke rises vertically.” At Beaufort 3, a gentle breeze, one sees “leaves and small twigs in constant motion.” At Beaufort 5, a fresh breeze, “small trees in leaf begin to sway; crested wavelets form on inland waters.” The poetic descxtions connect subjective impressions to obxtive reality. A near-gale—a Beaufort 7—is defined by “whole trees in motion; inconvenience in walking against wind.” See and feel those things, and you know that the wind is between thirty-two and thirty-eight miles per hour.

1805年，爱尔兰水文学家弗朗西斯·博福特爵士开发了一个通过观察测量海上风速的标尺。后来，它被调整为在陆地上使用。斯科特·胡勒在他2004年出版的《风的定义》一书中认为，该标尺附带的由无名氏创作的描述应该算作文学作品。在蒲福0级，风是“平静的；烟雾垂直升起”。在蒲福3级，微风柔和，人们看到“树叶和小树枝在不断运动”。在蒲福5级，清新的微风，“落叶的小树开始摇摆；内陆水域形成波浪”。诗意的描述将主观印象与客观现实联系起来。疾风——蒲福7级——则是由“整棵树在运动；逆风行走不便”所定义。看到和感觉到这些东西，你就知道风速在每小时三十二至三十八英里之间。
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Atwater devised an analogous guide to snow. His language is evocative, but there’s less authority in the descxtions. “Unstable damp snow is tacky,” he wrote. “It slithers out from underfoot and rolls away in balls or slips blanketwise. . . . Well settled snow has good flotation and makes a clean, sharp track.” Snow is less forthcoming than the wind. Its chaos hides beneath the surface.

阿特沃特为雪设计了一套类似的指南。他的语言是令人回味的，但描述中的权威性较低。他写道：“不稳定的湿雪是粘稠的，它从脚下溜走，滚成球状或滑成毯状……稳定性好的雪具有良好的浮力，能形成干净、锐利的轨迹。”雪没有风那么容易吐露讯息。它的混乱隐藏在表面之下。

One crisp, bright morning in February, I walked along a brook just outside the center of Davos, toward the headquarters of the Swiss Institute for Snow and Avalanche Research. In Davos, the train from the valley potters up through wooded hills, picking up locals in ski boots; the S.L.F., as the institute is now known, occupies a squat building a few minutes from the train station. A small exhibit in the lobby explains the history of snow and avalanches in Switzerland.

二月的一个清晨，我沿着达沃斯中心外的一条小溪走去，向瑞士雪崩研究所的总部走去。在达沃斯，来自山谷的火车穿过林立的山丘，接载穿着滑雪靴的当地人；雪崩研究所在距离火车站几分钟的地方占据了一栋简陋的建筑。大厅里的一个小展览解释了瑞士的雪和雪崩的历史。

In 1951, while Atwater was experimenting with explosives, Switzerland experienced the worst avalanche season in its recorded history. Ten feet of snow fell in ten days. About a hundred people were killed; villages that had survived avalanches for centuries were destroyed. The S.L.F., which was founded in 1942, suddenly became an institution of national import.

1951年，当阿特沃特正在进行炸药实验时，瑞士经历了有史以来最严重的雪崩季节。十天内下了十英尺的雪。大约一百人丧生；在雪崩中幸存了几个世纪的村庄被摧毁了。成立于1942年的雪崩研究所突然成为一个具有国家意义的机构。

Henning Löwe, the forty-six-year-old head of the institute’s Cold Lab, wears an earring in his right ear; before taking up the study of snow, he received a Ph.D. in theoretical condensed-matter physics. Dressed in jeans, black Nikes, and a worn fleece shirt, he led me inside the lab, where computers sat beside refrigerated rooms with three-inch-thick steel doors. The lab’s goal, he explained, was to find out what the wetness or heaviness or hoariness of snow really meant, on the level of its crystals. “We are connecting physical properties of snow to structure,” Löwe said. He picked up a palm-size cube that looked elaborately hollowed out, like a plaster mold of a termite’s nest. A twenty-millimetre-wide sample of snow had been taken from the crown of an avalanche—the pit that’s left when a slab releases—scanned with X-rays, and then 3-D-printed in plastic, at high magnification: the layer cake, under a microscope. The weak, bottom layer was composed of what looked like large popcorn kernels. The top layer, which had settled, was a tight tangle, like instant ramen. “You start to shear this thing”—Löwe made a chopping motion where the two layers met—“it’s ninety-nine per cent sure that this will break there.”

亨宁·洛维，这位46岁的研究所寒冷实验室的负责人右耳戴着一个耳环；在从事雪的研究之前，他获得了理论凝聚物质物理学的博士学位。他穿着牛仔裤、黑色耐克鞋和一件破旧的羊毛衫，把我领进实验室，实验室里的电脑就放在有三英寸厚的钢门的冷藏室旁边。他解释说，实验室的目标是在其晶体层面上找出雪的湿润、沉重或粗糙的真正含义。“我们正在将雪的物理特性与结构联系起来”，洛维说道。他拿起一个手掌大小的立方体，看起来已经被精心挖空了，就像白蚁巢的石膏模型。一个20毫米宽的雪样被从雪崩的顶部取下——用X射线扫描雪层时留下的坑，然后用塑料在高倍镜下进行三维打印：这是显微镜下的夹心蛋糕。脆弱的底层是由看起来像大爆米花核的东西组成的。已经沉淀下来的顶层是一个紧密的雪团，就像即食拉面。“如果我们开始剪切这个东西”——洛维在两个雪层相接的地方做了一个切割的动作——“它就有百分之九十九的把握会在那里破裂开来”。

Snow science has come a long way since Atwater’s experiments at Alta. The basic process by which newly fallen snow crystals sinter into a cohesive slab can now be seen in slow motion: it resembles the way ice cubes in an empty glass fuse together. The process of recrystallization—the re-separating of the cubes—was more mysterious. Löwe opened a closet, and pulled a cylinder from a shelf marked “Snowbreeder 3.” The device allows scientists to observe a snow sample while applying varying degrees of heat and pressure. At his computer, Löwe played a time-lapse video of “snow metamorphism” in the Snowbreeder. “In the beginning, it’s typical snow, it’s round-grained snow, the crystals are small,” he said. Then heat was applied from below. The lower crystals began evaporating their moisture to the crystals above, which used it to grow downward. “We see that, here, a facet’s growing. There, a facet’s growing,” he said, pointing. This was hoar—the snow becoming spiky, brittle, weak. “Seeing something is always the beginning of understanding,” he said.

自阿特沃特在阿尔塔的实验以来，雪的科学已经有了长足的进步。现在可以在慢动作中看到新落下的雪的晶体融结成粘性板块的基本过程：它类似于空杯子中的冰块融合在一起的方式。再结晶的过程——冰块的重新分离——更加神秘。洛维打开一个壁橱，从一个标有“Snowbreeder 3”的架子上拿出一个圆筒。该设备允许科学家在施加不同程度的热量和压力的同时观察雪样。在他的电脑前，洛维在Snowbreeder中播放了一段“雪的变质”的延时视频。他说：“一开始，它是典型的雪，它是圆形颗粒的雪，晶体很小。”然后从下面施加热量。下面的晶体开始向上面的晶体蒸发它们的水分，上面的晶体利用它向下生长。“我们看到，这里，一个切面正在生长”，他指着那里说道。这是白霜——雪变得尖尖的、脆脆的、非常脆弱。他说：“所见总是理解的开始。

The scientific study of snow layers has refined our understanding of avalanches. In 2008, a study published in Science by a group of Scottish and German materials researchers modelled how, when one part of a heavy layer of snow collapses onto a weak layer, it can produce a wave. Their model explained a curious observation from the field: skiers occasionally trigger deadly avalanches above or below them, even when standing on flat slopes. The weak layer, it turns out, behaves like the coils in a mattress: apply force in one place, and it spreads all over the bed. The concept is now a cornerstone of avalanche-safety education, where it is known simply as “remote triggering.”

对雪层的科学研究已经完善了我们对雪崩的理解。2008年，一组苏格兰和德国的材料研究人员在《科学》杂志上发表了一项研究，模拟了当厚重的雪层的一部分坍塌到一个薄弱的雪层上时，如何产生波浪。他们的模型解释了现场的一个奇怪的观察结果：滑雪者偶尔会在他们上方或下方引发致命的雪崩，即使是站在平坦的斜坡上。事实证明，薄弱层的行为就像床垫中的线圈：在一个地方施力，它就会散布到整个床上。这个概念现在是雪崩安全教育的一个基石，在那里它被简单地称为“远程触发”。

Snow research also has applications beyond avalanches. Spinning his keys around a finger, Löwe led me through the cold rooms. In one, a humidifier generated tiny clouds of perfect, lab-grown powder; in another, snow from the Arctic, Finland, and Iceland had been carefully preserved. Scientists are studying how snow’s crystal structure determines its color, or “albedo,” which, in turn, affects its ability to act like a giant mirror and mitigate global warming.

雪地研究也有雪崩以外的应用。洛维用手指旋转着他的钥匙，带我参观了这些寒冷的房间。在一个房间里，一个加湿器产生了完美的、实验室培育的粉末的小云团；在另一个房间里，来自北极、芬兰和冰岛的雪被精心保存起来。科学家们正在研究雪的晶体结构如何决定其颜色，或“反照率”，这反过来又影响其如同一面巨大的镜子和缓解全球变暖的能力。

In an upstairs office with mountain views, Perry Bartelt, a gray-haired research engineer, works on Rapid Mass Movement Simulation, or ramms—software for simulating avalanches. The week before, an avalanche in Turkey had killed half a dozen people; dozens more died during the rescue, when the mountain avalanched a second time. Turkish researchers had rushed data from both slides to Bartelt. ramms calculated that the first avalanche had hit the bottom of the slope with five times the force needed to knock down a building. Its core had the density of wood.

在楼上一间可以看到山景的办公室里，白发苍苍的研究工程师佩里·巴特尔正在进行快速大规模运动模拟，即ramms——这是一款模拟雪崩的软件。一周前，土耳其的一场雪崩造成6人死亡；在救援过程中，山体第二次雪崩，又有数十人死亡。土耳其研究人员急忙将两次雪崩的数据交给了巴特尔。快速大规模运动模拟软件计算出，第一次雪崩撞击坡底的力量是推倒一座建筑所需力量的五倍。它的核心部分具有木材的密度。
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Using a terrain map, ramms predicts the path and the power of an avalanche. Its central innovation is its ability to treat an avalanche as a “granular shear flow,” using statistics to average out the activity of millions of interacting grains. Imagine a box of cereal, full of flakes and marshmallows; now pour it out. Some bits will fly straight, carried by their own momentum. Others will catch on the surface they’re sliding down. Many flakes will shake against one another, breaking up and settling below the intact marshmallows. (In granular flows, small things sink beneath bigger ones.) ramms seeks to predict the outcome of this churn.

使用地形图，快速大规模运动模拟软件预测了雪崩的路径和力量。它的核心创新是它能够将雪崩视为 "颗粒剪切流"，利用统计学来平均化数百万相互作用的雪粒的运动。想象一下一盒麦片，里面装满了片状物和棉花糖；现在把它倒出来。一些碎片会直接飞起来，被它们自己的动力带着。其他的会被它们滑下去的表面抓住。许多片状物会相互摇晃，碎裂并沉淀在完整的棉花糖下面。（在颗粒状的流动中，小东西会在大东西下面沉下去。）快速大规模运动模拟软件试图预测这种搅动的结果。

The software was validated on historical avalanches—especially on data about whether trees had been knocked down, and, if so, how old they were. “Trees are wonderful mechanical sensors,” Bartelt said. If an avalanche takes down a seventy-year-old stand of trees, you know that the avalanche has a return period of at least seventy years. Fine-tuning the model would require more precise data, which are hard to come by. Gathering this information would require taking readings inside, or under, an avalanche.

该软件在历史雪崩中得到了验证——特别是关于树木是否被撞倒的数据，如果是的话，它们的年龄有多大。巴特尔说道：“树木是奇妙的机械传感器。如果雪崩撞倒了一棵有七十年树龄的树木，你就知道雪崩的回归期至少有七十年。对模型进行微调将需要更精确的数据，而这些数据很难得到。收集这些信息将需要在雪崩内部或下方进行读数。

For this purpose, the S.L.F. maintains an avalanche test site in the Vallée de la Sionne—a steep, mountainous area about two hundred miles from Davos. Hearing the phrase “test site,” one might imagine a bunny slope. Actually, it is an enormous mountain, improbably reserved for science.

为此，雪崩研究所在雄恩峡谷维持着一个雪崩试验场——这是一片离达沃斯约200英里的陡峭山区。听到 “试验场“这个短语，人们可能会想到一块平缓滑雪坡。但实际上，它是一座不可能是为科学保留的巨大的山。

The site’s chief scientist is Betty Sovilla, a hydraulics engineer. When we met at S.L.F., she was wearing red-frxd glasses, a black cardigan, jeans, and red boots. “ramms is a very simplified model,” she said. The goal of the test site was to develop a more realistic version, by correlating detailed measurements of the snow cover with the avalanches it created. She was particularly interested in glide avalanches: there were more of them every year, but they were elusive. “You cannot predict when they are released,” she said. “This is really the avalanche of the future.”

该基地的首席科学家是贝蒂·索维拉，她是一位水力学工程师。当我们在雪崩研究所见面时，她戴着红框眼镜，穿着黑色开衫、牛仔裤和红色靴子。“快速大规模运动模拟软件是一个非常简化的模型，”她说。试验场的目标是开发一个更真实的版本，通过对雪层的详细测量与它所产生的雪崩相关联。她对滑动雪崩特别感兴趣：每年都有更多的滑动雪崩，但它们难以捉摸。她说：“你无法预测它们何时被释放。这确实是未来的雪崩。”

One morning, Pierre Huguenin, a forty-nine-year-old mountaineer and snow scientist, drove me to the site in a white Mitsubishi Pajero. “You see the flakes. You see the crystals,” he said, gesturing out the window. There had been a storm the previous night. He stopped the car where the road ended, and we changed into snowshoes.

一天早上，四十九岁的登山家和雪地科学家皮埃尔·胡戈宁开着一辆白色的三菱帕杰罗载我到现场。“你看到了雪花。你看到了晶体，”他说着，指向了窗外。前一天晚上有一场暴风雨。他把车停在路的尽头，我们换上了雪鞋。

Outside, there was about a foot of pristine powder. I stooped and ran my hand through it. Bone-dry, it was the pure bright white of confectioner’s sugar, with the texture of sea salt. Huguenin pulled out his phone. The avalanche forecast for the area had us covered in orange. “We are in the third degree,” he said—the risk category in which the most avalanche deaths occur in the Alps, equivalent to the American “considerable.” He pulled out two avalanche beacons—transmitters that would relay our location to rescuers—and set them to Send. We strapped them under our jackets.

外面有大约一英尺厚的原始雪粉。我弯下腰，用手摸了摸。它的颜色像糖果的纯白色，又有海盐的质地。胡戈宁掏出他的手机。该地区的雪崩预报将我们覆盖在橙色地区。他说：“我们处于第三级”，这是阿尔卑斯山雪崩死亡人数最多的风险类别，相当于美国人所说的“非常严重的程度”。他拿出两个雪崩信标——即可以向救援人员传递我们位置的发射器——并将它们设置为发送信号状态。我们把它们绑在我们的外套下面。

“My job before working at the S.L.F. was at a cement plant,” Huguenin said, as we set out. (He was an engineer there.) “It was so loud.” Now we could hear the river as we walked. Beneath the blue sky, ours were the only tracks. After twenty minutes, the site came into view: a broad, bare mountainside, eight thousand feet high. Between two couloirs—the main avalanche paths—a half-dozen chalets huddled near a small wood.

“我在雪崩研究所工作之前的工作位于一家水泥厂”，胡戈宁在我们出发时说道。（他是那里的工程师。）“那里太吵了。”现在，我们可以边走边听到河水的声音。在蓝色的天空下，我们的足迹是唯一的痕迹。二十分钟后，那个地点出现在眼前：是一个宽阔且光秃秃的山坡，高达八千英尺。在两条雪道（主要的雪崩通道）之间有六座木屋蜷缩在一片小树林附近。

“They are not allowed to live here in the winter,” Huguenin said. Two days earlier, there had been a naturally occurring glide avalanche at the site. I asked whether it had been dangerous. “You would be dead,” he said. “No chance.”

“他们在冬天不允许住在这里”，胡戈宁说道。两天前，该地曾发生过一次自然的滑坡雪崩。我问它是否有危险。“你会死的”，他说，“没有机会逃生”。

The site was built in 1997; in the winter of 1999, the snow was the heaviest it had been since 1951—perfect conditions for an experiment. Using explosives dropped from a helicopter, the S.L.F. triggered three avalanches in the course of a month. They were so massive that they destroyed most of the institute’s equipment. If you had been skiing on the mountain during the last avalanche, you might have heard a soft exhalation: air releasing from a crack in the slab. Upslope, it would have looked as though someone had slit the mountain’s forehead. Now its face was falling off; the break, nine football fields across, was as deep as eleven feet in places. Blocks of snow would begin leaping up prettily, breaking like roiling water. In the quiet, you might feel something lapping at the back of your legs before being swept off your feet.

这块场地建于1997年；1999年冬天的降雪是1951年以来最厚的一次——这是进行实验的完美条件。雪崩研究所使用从直升机上投放的炸药，在一个月内引发了三次雪崩。它们的规模是如此巨大，以至于摧毁了该研究所的大部分设备。如果你在最后一次雪崩期间在山上滑雪，你可能会听到轻轻的呼气声：空气从石板的裂缝中释放出来。在斜坡上，看起来就像有人在山的额头上划了一刀。现在，它的脸正在脱落；裂缝有九个足球场那么宽，有些地方深达11英尺。块状的雪开始跃起，划出漂亮的曲线，像沸腾的水一样破碎。在安静的环境中，你可能会感觉到有什么东西在你的腿后面拍打，然后你就被卷走了。

The slide generated a powder cloud nearly two hundred feet high. It seemed to move in slow motion, like dry ice billowing, but it levelled the trees. Underneath, the core was formed by four hundred thousand tons of snow. Huguenin asked me to visualize the test peak, two kilometres distant, and the peak of the mountain on which we stood as the two sides of a half-pipe. With a deep roar, he said, the avalanche had run through the valley like a skateboarder, with enough speed to climb the other side.

滑道产生了近两百英尺高的粉末云。它似乎在进行慢动作的移动，就像干冰在滚动，但它把树木夷为平地。表面之下的核心是由四十万吨的雪形成的。胡戈宁让我把两公里外的实验山峰和我们所站的山峰想象成一条半管滑道的两边。他说，随着一声低沉的吼叫，雪崩像滑板运动员一样穿过山谷，以足够的速度爬上另一边。

“It came all the way up there?” I asked, pointing to the top of our peak, three hours’ hike away.

“它一路来到那里？”我指着我们徒步三个小时才抵达的山顶问道。

“Yup, and there is a trail there. One of the wards was on it. The guy at that time saw a huge amount of snow jumping the top here”—he motioned toward the ridgeline above us—“and falling on the other side.” As the snow poured over the ridge, the warden could hear tree trunks snapping like matchsticks. “He really thought he was going to die,” Huguenin said. The experiment, which destroyed much of the forest, didn’t go over well with the locals.

“是的，而且那里有一条小路。其中一个监视员就在上面。当时那个人看到大量的雪跃到这里的山顶上”——他指向我们上方的山脊线——“并落在了另一边”。当雪倾泻在山脊上时，监视员可以听到树干像火柴棍一样折断的声音。“他真的以为自己死期将至”，胡戈宁说道。这个实验摧毁了大部分的森林，当地人对它很不满。

Huguenin and I continued walking. To our left, a Soviet-looking bunker poked out of the hill. It was two stories tall; in the 1999 experiment, it had been covered by thirteen feet of snow. To reach the observers buried inside, a crew had to cut a vertical tunnel with a chainsaw. Near the bunker, an array of continuous-wave radar antennas, designed to measure the flow at the avalanche’s core, craned toward the peak. Huguenin pointed to “obstacles” on the slope—pressure and velocity sensors mounted on concrete-and-steel structures. Against the mountainside, the largest obstacle, a sixty-foot-tall pylon studded with flow-measurement devices, looked like a toothpick.

胡戈宁和我继续向前走。在我们的左边，一个看起来像苏联人碉堡的建筑从山上探出头来。它有两层楼高；在1999年的实验中，它已经被13英尺的雪覆盖。为了接近埋在里面的观察员，工作人员不得不用电锯切开一条垂直的隧道。在掩体附近，有一个连续波雷达天线阵列，旨在测量雪崩核心的流量，并向山峰方向伸展。胡戈宁指着斜坡上的“障碍”——那是安装在混凝土和钢结构上的压力和速度传感器。在山坡上，最大的障碍物是一个60英尺高的塔架，上面镶有流量测量装置，它看起来像一根牙签。

Avalanche country is like bear country. The threat hardly ever comes, but it defines the place, and lends it its grandeur. Outside the bunker, the mountains rose around us; flat clouds gathered in a distant valley like steam. We had lunch: bread, cheese, chocolate. The snow was warming in the sun. Scooping it up, I found that, instead of seeping through my fingers, it now formed a perfect snowball—metamorphism within a matter of hours. I thought of how plants observed in time lapse seem to move with animal purpose. I imagined the crystals in this newly fallen snow sintering and crackling with life.

雪崩地区就像熊出没之地。威胁几乎不会到来，但它却定义了这个地方，并赋予它宏伟的气势。在掩体外，山脉在我们周围升起；平坦的云层像蒸汽一样聚集在远处的山谷里。我们吃了午饭：面包、奶酪、巧克力。雪在阳光下变暖。我把它舀起来，发现它不再从我的手指缝中渗出，而是在几小时内形成了一个完美的雪球——它在变形。我想到了在延时摄影中观察到的植物似乎是带着动物性的目的移动的。我想象着这些新落下的雪中的晶体在融结，发出噼里啪啦的声音。
原创翻译：龙腾网 http://www.ltaaa.cn 转载请注明出处


From where we were sitting, we could see the glide avalanche from two days earlier. It was hard to get a sense of scale. Huguenin handed me his binoculars. Through them, I saw chest-high boulders of snow. Without them, the avalanche was a scratch on the mountainside.

从我们坐的地方，我们可以看到两天前的滑动雪崩。这很难让人感受到它的规模。胡戈宁把他的双筒望远镜递给我。通过望远镜，我看到了齐胸高的雪垒成的巨石。如果没有望远镜，雪崩只是山坡上的一道划痕。

One is unlikely to encounter an avalanche on the bomb-cleared trails of a ski resort like Alta. Avalanche accidents happen far more often in the backcountry, where skiers search for what the First Nations author Richard Wagamese called “the great white sanctity of winter.” In a recent survey, more than half of backcountry skiers said they had triggered an avalanche; a quarter said they’d got caught in one. It’s telling that the standard kit separating them from resort vacationers consists of a beacon, a probe, and a shovel.

在阿尔塔这样的滑雪胜地，人们不太可能在已清除炸弹的小路上遇到雪崩。雪崩事故更经常发生在野外，在那里，滑雪者寻找《第一民族》的作者理查德·瓦加梅斯所说的“冬天的伟大白色圣地”。在最近的一项调查中，超过一半的越野滑雪者说他们曾引发过雪崩；四分之一的人说他们曾被卷入雪崩。这说明，将他们与度假区度假者区分开来的标准装备包括一个信标、一个探测器和一把铁锹。

I grew up skiing at small mountains in the Laurentians, just north of Montreal. Well groomed and popular, they were often scraped to ice. It was only a few years ago that I went with a friend to a large ski resort in Colorado. One day, we travelled to a remote part of the mountain. There had been fresh snow that morning, and I whooped as I dropped in, not another soul in sight. The snow felt like a cloud underfoot; falling evoked the childhood joy of jumping in leaves. Carving slow curves, I recognized the feeling of discovery: I was writing my name on the mountain. I also understood, for the first time, how powder and silence lure skiers into the backcountry.

我从小就在蒙特利尔北部的劳伦蒂斯山脉的小山上滑雪。这些山峰修整得很好，很受欢迎，经常被滑成冰道。只是在几年前，我和一个朋友去了科罗拉多州的一个大型滑雪场。有一天，我们去了山上的一个偏远地区。那天早上下起了新雪，我一落脚就大声呼喊，目光所及没有一个人。雪感觉就像脚下的云；落下时唤起了我童年时在树上跳跃的快乐。在缓慢的弯道上，我认识到这种发现的感觉。我在山上写下了自己的名字。我也第一次明白，雪粉和寂静是如何引诱滑雪者进入雪地深处的。

To some extent, backcountry skiers can rely on avalanche forecasts. At the Utah Avalanche Center (motto: “Keeping You on Top”), forecasters make daily field observations (“+” means fresh snow; “.” round grains; “Ʌ,” depth hoar), integrating them into uncannily specific recommendations: “It remains possible to trigger a wind slab avalanche. . . . This snow will feel upside down and stiff.” Different kinds of terrain are assigned levels of danger, on a one-to-five scale; colorful diagrams with cartoon icons show which parts of the mountain—above the treeline, say, or southern aspects—are to be avoided.

越野滑雪者在某种程度上可以依靠雪崩预报。在犹他州雪崩中心（其座右铭是：“让你站在顶峰上”），预报员每天进行实地观察（“+”表示新雪；“.”表示雪籽；“Ʌ”表示深度结霜），将它们整合成令人难以置信的具体建议：“仍然有可能引发风成板状雪崩……这种雪会让人感到上下颠倒和僵硬。”不同类型的地形被划分为一至五级的危险等级；带有卡通图标的彩色图表标识了山体的各个部分——比如说在树木生长线以上的地区，或者南坡区域——是应该避免前往的。

Some experts worry that such diagrams give skiers a false sense of security. My sixty-seven-year-old godfather, Richard, happens to be the most experienced backcountry adventurer I know; a snowboarder for decades, he has logged more than a hundred thousand vertical metres in the past two years, in Kashmir, Antarctica, and other places. In the backcountry, he relies not just on forecasts but also on guides, to whom he attributes extraordinary diagnostic powers. Before taking a group out, a guide might dig a small column out of the slope. He’ll examine the layers, sussing out weakness, assessing the look of the crystal grains. Then he’ll tap the top of the column with his hand ten times, bending from the wrist. If the column survives, he’ll do it again, bending from the elbow; finally, he’ll do it from the shoulder. His interest is in when the column collapses, and how. Once, on a slope that seemed risky, a guide told Richard’s group that, whatever they did, they must follow, one by one, to the right of his line. Each skier followed in turn, carefully staying to his right. As Richard descended, a layer of snow unsettled beneath him, a few feet to the left of the guide’s tracks, and sent a wave across the bowl. The slope fell like a sheet.

一些专家担心，这样的图示会给滑雪者带来虚假的安全感。我六十七岁的教父理查德恰好是我认识的最有经验的越野冒险家；他玩了几十年的滑雪，在过去两年里，他在克什米尔、南极洲和其他地方进行了十多万米的垂直化学。在雪地深处，他不仅依靠预测，还依靠向导，他把非凡的判断能力归功于他们。在带一个小组出去之前，向导可能会从斜坡上挖出一个小圆柱。他将检查各层，找出弱点，评估晶体颗粒的外观。然后他用手敲击柱子的顶部十次，从手腕处开始弯曲。如果柱子还在，他将再次这样做，从肘部开始弯曲；最后，他将从肩部开始做。他的兴趣在于柱子何时倒塌，以及如何倒塌。有一次，在一个看起来很危险的斜坡上，一个向导告诉理查德的团队，无论他们做什么，他们必须一个一个地跟在他的队伍右边。每个滑雪者依次跟上，小心翼翼地呆在他的右边。当理查德下降时，在他脚下，在向导的足迹左边几英尺的地方，有一层雪松动了，并在低洼地区掀起了波浪。斜坡上的雪呈片状滑下去。

One way to avoid avalanches is to ski shallower slopes. Slopes of around twenty-five degrees are perfectly enjoyable; steeper ones are only marginally more fun. And yet it’s hard for skiers to hold back. “The tricky part is controlling our lust,” a forecast reads. After a student of his died in an avalanche, Jordy Hendrikx, a professor at Montana State University, shifted his focus from geophysical research to behavioral science. (“Understanding how a crystal grows is not enough to change the current fatality profile,” he told me.) In one long-running study, he had a large group of backcountry skiers log their activity with a G.P.S.-enabled app. He found that experts chose steeper terrain, as did all-male groups, especially younger ones. (“Quantifying the obvious,” he has said.) When Tremper published his book, in 2008, he reported that, although a third of those who used the backcountry in Utah were women, women accounted for only 3.3 per cent of fatal accidents.

避免雪崩的一个方法是滑较浅的山坡。二十五度左右的斜坡是完全可以纵情享受的；更陡峭的斜坡只会增加一点乐趣。然而滑雪者却很难安耐得住。“最棘手是控制我们的欲望，”一份预报中如此写道。在他的一个学生死于雪崩之后，蒙大拿州立大学的教授乔迪·亨德利克斯将他的注意力从地球物理研究转移到了行为科学上。（他告诉我说：“了解晶体的生长过程并不足以改变目前的死亡状况”。）在一项长期的研究中，他让一大群越野滑雪者用一个支持全球定位系统的应用程序记录他们的活动。他发现，滑雪行家们选择了更陡峭的地形，所有男性群体也是如此，尤其是年轻群体。(他说：“量化显而易见的事实”。)当特伦普在2008年出版他的书时，他报告说，尽管在犹他州越野滑雪的人中有三分之一是女性，但女性只占致命事故的3.3％。

In the early two-thousands, when no amount of snow science seemed to be improving outcomes, the study of “human factors” that contributed to avalanche accidents became popular. Tremper lists six common “heuristic traps” that lead to avalanche fatalities: doing what is familiar; being committed to a goal, identity, or belief; following an “expert”; showing off when others are watching; competing for fresh powder; and seeking to be accepted by a group. The Swiss pocket guide for backcountry skiers is full of technical information about slabs and slope angles, but it also includes the advice “Don’t give in to temptation!”

在21世纪00年代早期，当任何数量的雪的科学似乎都无法改善结果时，对导致雪崩事故的“人为因素”的研究开始流行。特伦普列出了导致雪崩死亡的六个常见的“启发式陷阱”：做熟悉的事情；致力于一个目标、身份或信仰；跟随“行家”；在别人观看时炫耀；争抢新鲜雪粉；以及寻求被团体接受。瑞士越野滑雪者袖珍指南中充满了关于石板和斜坡角度的技术信息，但也包括“不要向诱惑屈服”的建议。

New pilots are said to be most accident-prone right after their hundred- and-fiftieth hour; that’s when self-confidence peaks. Dave Richards, the Alta avalanche director, told me that, for many skiers, danger is highest right after the completion of an avalanche-avoidance course. The backcountry is what behavioral scientists call a “wicked” environment for learning: it gives you no negative feedback until it kills you.

据说，新飞行员在第150小时后最容易发生事故；那是自信心的高峰期。阿尔塔雪崩主管戴夫·理查兹告诉我，对许多滑雪者来说，在完成雪崩规避课程后，危险性最高。雪地深处是行为科学家所谓的“邪恶”的学习环境：它不给你任何负面反馈，直到它杀死你。

A database maintained by the Colorado Avalanche Information Center contains aviation-style tick-tock accounts of avalanche fatalities. In January, 2019, a group of skiers taking a backcountry avalanche course went out with their instructor for a day in the field. The skiers followed a methodical, rigorous plan. At predetermined waypoints, the group assessed the conditions; they dug a snow pit, testing a snow column for strength. Their plan for the day included slope angles for all the terrain they might encounter. But they didn’t measure the steepness in the field themselves, and one particular slope that they believed to be no more than twenty-nine degrees was actually thirty-two degrees. As the second of six skiers proceeded downward, the other four, waiting above, sidestepped in order to see his progress more clearly. The slope avalanched twice—the first one remote-triggered the second—and the second skier was buried.

科罗拉多雪崩信息中心维护的一个数据库包含了雪崩致人死亡的航空钟记录。2019年1月，一群参加越野雪崩课程的滑雪者与他们的教官一起出去实地考察了一天。滑雪者们遵循一个有条不紊的严格计划行进。在预先确定的地点，该小组评估了条件；他们挖了一个雪坑，测试雪柱的强度。他们当天的计划包括他们可能遇到的所有地形的坡度角。但是他们并没有亲自测量现场的坡度，而其中一个斜坡——他们认为不超过29度——实际上是32度。当六个滑雪者中的第二个人向下走时，在上面等待的另外四个人侧身避开，以便更清楚地看到他的进展。山坡上发生了两次雪崩，第一次雪崩远远地触发了第二次雪崩，第二个滑雪者被埋在了雪中。

Two skiers turned their beacons to Search, monitoring their screens. They assembled their tent-pole-like probes, jamming them into the ground until they struck the buried skier. It took more than twenty-five minutes to shovel the victim out. The report, which identifies “a Persistent Slab avalanche problem,” is longer than most, at pains to explain why this group—so well informed and meticulous—could still be caught.

两名滑雪者将他们的信标转向搜索模式，监测他们的屏幕。他们组装了他们的帐篷杆一样的探测器，把它们塞进地面，直到它们击中被埋的滑雪者。他们花了超过二十五分钟才将受害者铲出来。这份报告指出了 “持续的板状雪崩问题”，它比大多数报告都要长，不厌其烦地解释为什么这群人——消息如此灵通、如此一丝不苟——仍然会撞上雪崩。

On my first night at Alta, I stayed at one of the lodges. Since the road had closed, the cheap dorms filled up, four to a room. One man, Bill, forty-five years old, took a bottom bunk. A week earlier, he’d been in an avalanche—small, he said, and soft-slab. I asked him what it was like. “Manageable, and managed,” he said. He’d realized that the slope had the potential to slide, but he knew what to do if that happened, so he skied it anyway. “I did a couple tomahawks,” he said—tumbling end over end for three hundred feet, then standing up. Was he shaken? He thought about it. Actually, he said, he was serene. “Manageable, and managed,” he repeated, from his bed.

在阿尔塔的第一个晚上，我住在其中一个旅馆里。由于道路已经关闭，廉价的房间内已经满员，当时是四个人一个房间。一个叫比尔的人，四十五岁，住在下铺。一周前，他经历了一次雪崩——他说，规模很小，而且是软性板状雪崩。我问他那是什么感受。他说：“可以应付，而且我应付过来了”。他意识到这个斜坡有可能滑动，但他知道如果发生这种情况该怎么做，所以他还是滑了过去。“我做了几个战斧式的动作”，他说道——在三百英尺的距离内翻来覆去，然后站起来。他是不是被吓到了？他想了想。事实上，他说道，当时他很平静。他在床上重复说着：“可以应付，而且我应付过来了”。

Toward the end of my time in Switzerland, I spent the day with Stefan Margreth, S.L.F.’s chief civil engineer. Easygoing, he wore a pink-and-red winter hat. At the institute, Margreth is the spiritual descendant of Johann Coaz: he carries Switzerland’s avalanche-hazard maps in his head. Margreth sometimes uses ramms to model avalanche risk. “It’s a great honor that he even uses the program,” Bartelt, its creator, said.

当我在瑞士的时间即将结束时，我和雪崩研究所的首席土木工程师斯特凡·马格雷特共处了一天。他很随和，戴着一顶粉红色的冬帽。在研究所，马格雷特是约翰·科兹的精神后裔：他脑子里装着瑞士的雪崩危险地图。马格雷特有时会用快速大规模运动模拟软件来模拟雪崩风险。“他在使用这个程序，这对我而言是一个巨大的荣誉”，该软件的发明者巴特尔说道。

Many Swiss towns have building restrictions based on avalanche-hazard maps. “Everyone in the Swiss mountains knows their red zones and blue zones,” Margreth told me. We drove to St. Antönien, a tiny farming village an hour outside Davos. The threat of avalanche there is so great that, in storms, residents wear beacons while tending their farms. Margreth helped design or approve nearly every avalanche-mitigation measure in town: a huge concrete wedge on the upslope side of the elementary school; vast lines of steel girders high in the starting zones; houses built into the sides of hills, so that snow slides right over them.

许多瑞士城镇都有基于雪崩危险地图的建筑限制。马格雷特告诉我，“瑞士山区的每个人都知道他们的红区和蓝区”。我们驱车前往达沃斯外一小时车程的圣安托尼恩，这是一个小小的农业村。那里的雪崩威胁如此之大，以至于在暴风雨中，居民们在打理农场时都要佩戴信标。马格雷特帮助设计或批准了镇上几乎所有的雪崩缓解措施：在小学的上坡一侧有一个巨大的混凝土楔子；在雪崩爆发区高处有大量的钢梁；房屋建在山的两侧，这样雪就会从它们上面滑过。

After the winter of 1951, a party from the federal government in Bern travelled to St. Antönien to discuss the question of resettlement. The townspeople wanted to stay. “The Swiss mentality is to let people live in the mountains,” Margreth said. Taxpayers spent millions of dollars on mitigation measures; roads running up the mountain had to be built just to transport construction equipment. I asked Margreth why people had moved to St. Antönien in the first place. “The good places had been taken,” he said, smiling. In Switzerland, even the mountains are crowded.

1951年冬天过后，伯尔尼联邦政府的一个代表团来到圣安托尼恩，讨论重新安置当地居民的问题。镇民们想留下来。马格雷特说：“瑞士人的心态是让人们住在山里”。纳税人花了几百万美元来采取缓解措施；为了运输建筑设备，不得不修建上山的道路。我问马格雷特，为什么人们最初搬到了圣安托尼恩。他笑着说：“好地方都被占了。在瑞士，即使是山区也很拥挤”。

A few years back, Margreth was contacted by the emergency-programs manager and avalanche forecaster for the city of Juneau, Alaska. Several neighborhoods were in the runout zones of slide paths; it was probably the most significant avalanche problem in the United States. Could anything be done? Even if tens of millions of dollars were spent on mitigation, the houses could not be completely protected; their destruction was more or less inevitable. Margreth suggested that the city buy the owners out and keep people from building new homes. So far, this has proved politically impossible; the city of Juneau, which had already bought a few empty lots in the area, has invested in warning systems and road-protection protocols.

几年前，阿拉斯加朱诺市的应急计划经理和雪崩预报员联系了马格雷特。有几个街区位于滑道的冲出区；这可能是美国最严重的雪崩问题。有什么办法吗？即使花费数千万美元用于减灾，这些房屋也不可能得到完全的保护；它们的毁灭或多或少是不可避免的。马格雷特建议城市将业主的产业买下来，不让人们再建新房。到目前为止，这在政治上被证明是不可能的；朱诺市已经买下了该地区的几块空地，在警告系统和道路保护协议方面进行了投资。

“Sometimes you need accidents,” Margreth said. Atwater, in his book, suggests that “people need a good scare not less than every three years. Otherwise they begin to think that avalanche hazard is a figment of someone’s imagination.”

“有时你需要事故”，马格雷特说道。阿特沃特在他的书中建议，“人们需要不少于每三年一次的良性恐吓。否则他们就会开始认为雪崩危险是某人的臆想”。

They can seem absurd to us, these people living at the base of steep hills. Don’t they know they’re idling in the face of disaster? The feeling was in the air in Switzerland, though not because of avalanches. As we walked on the road toward the edge of town, we saw diners enjoying themselves at sidewalk tables. “It’s much too warm for a February day,” Margreth said, in the winter sun. It had been three years since the team at the test site performed an experiment. Not enough snow had fallen.

在我们看来，这些住在陡峭山脚下的人可能非常不可理喻。难道他们不知道他们在灾难面前毫无还手之力吗？瑞士的空气中弥漫着这种感觉，尽管不是因为雪崩。当我们走在通往城镇边缘的路上时，我们看到食客们在人行道上的桌子上享受生活。马格雷特在冬日的阳光下说：“对于二月的天来说，现在太温暖了”。自从试验场的团队进行实验以来，已经过去三年时间了。雪下得还不够多。

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