A twin-tip is a ski that is turned up (rockered) at both the tip and the tail, rather than only at the front, allowing the skier to ski, take off, and land switch (backwards) as easily as forwards. Developed for freestyle skiing, twin-tips make terrain park tricks, switch riding, and spinning in both directions possible, and the design has spread to all-mountain and powder skis for its versatility. The upturned tail is the defining feature.
Frame bindings are alpine-touring (AT) ski bindings in which the toe and heel pieces are connected by a rigid frame (rail) that pivots at the toe, lifting the whole boot-and-frame for uphill travel and locking flat for the descent. Their key advantages are broad boot compatibility (they work with standard alpine boots, not just tech boots) and a familiar, alpine-like downhill feel — but they're significantly heavier and less efficient on the uphill than tech bindings.
Tech bindings (also called pin bindings) are lightweight backcountry ski touring bindings that secure the boot with small metal pins engaging fittings in the toe and heel of compatible 'tech' boots, allowing a free-pivoting toe for efficient uphill travel and locking the heel down for the descent. Far lighter and more efficient for climbing than frame bindings, tech bindings are the standard for serious ski touring and ski mountaineering, though they require tech-compatible boots.
Sun cups are bowl- or cup-shaped hollows that form on a snow surface under intense sunlight, creating a honeycomb of depressions separated by thin ridges. They develop through uneven melting and sublimation — the hollows absorb and trap heat and melt faster while the ridges persist — and are common on high-altitude and spring/summer snowfields with strong sun. Sun cups range from small dimples to deep, foot-plus hollows that make foot, ski, and snowshoe travel awkward and tiring.
Firn is granular, compacted, partly consolidated snow that has survived at least one summer melt season without turning fully to ice — an intermediate stage between fresh snow and dense glacier ice. Through cycles of melting, refreezing, and compaction, snow crystals round and bond into denser firn, which over years can become glacier ice. Mountaineers and ski-mountaineers encounter firn high on snowfields and glaciers, where it offers firm, supportive, often pleasant travel and skiing.
Graupel is a form of precipitation consisting of soft, round, white pellets, formed when supercooled water droplets freeze onto falling snowflakes (a process called riming), creating small balls of rimed snow. Distinct from hail (which is harder, layered ice) and ordinary snow, graupel looks like tiny Styrofoam balls. In avalanche terms, a layer of round graupel can act like ball bearings in the snowpack, creating a sneaky weak layer that other snow can slide on.
Sastrugi are sharp, irregular ridges and grooves carved into a snow surface by strong, persistent wind, which erodes softer snow and leaves hard, wavelike formations aligned with the prevailing wind direction. Common on exposed alpine ridges, plateaus, and polar regions, sastrugi range from small ripples to large, hard ridges a foot or more high. They make travel by ski, foot, or sled rough, jarring, and tiring, and can indicate prevailing wind patterns.
Après-ski (French for 'after ski') is the social activity and culture that follows a day on the slopes — relaxing, eating, drinking, and socializing at bars, lodges, and restaurants around a ski resort. More than a single activity, it's a defining part of ski-town culture, ranging from a quiet drink by the fire to lively music and dancing in ski boots.
First tracks refers to being the first person to ski or ride down a slope of fresh, untouched snow, leaving the first lines in it. Coveted especially after a powder snowfall, first tracks offer the purest version of the floating powder experience before the snow gets tracked out by other skiers. People chase first tracks by arriving early for resort opening ('dawn patrol') or by touring into the backcountry.
A halfpipe is a U-shaped channel carved into the snow with steep walls, used by snowboarders and freestyle skiers to perform aerial tricks. Riders descend the pipe, using the momentum from each wall to launch above the lip, perform spins and grabs, and land back on the transition. A competitive Olympic discipline, the halfpipe rewards amplitude (height), difficulty, and execution of tricks.
