At certain latitudes, midwinter becomes all about perspective. Snow can be a hazard to driving, a ticket to slide, or one of nature's nicer decorative touches. But the white stuff can also be seen as building material. And you don't have to be 10 years old and thinking "snow fort."

Quinzees - hollowed-out mounds of snow, igloos without the blocks - were once widely used by Chipewyan hunters who had strayed far from their winter lodges in subarctic Canada. Today they're favored by intrepid wilderness campers who like working with natural resources - and who understand the insulating properties of snow.

Scout troops and high schools from Maine to Michigan turn the building of these short-term shelters into learning experiences. Dogs have been known to inhabit the snow huts with glee. Quinzees also have backyard-recreation potential. The experience is something like sand-castle building. Key difference: You get to go inside and hang out.

Gordon Baker once slept in a quinzee in temperatures of 25 degrees F. below zero. He and two friends lounged inside with a candle for light and felt comfortable wearing T-shirts. "If you have a shovel, a couple of friends with shovels, and a few sticks, you can make a big pile of snow and have a house in two hours," says Mr. Baker, a guide with Algonquin Outfitters in Oxtongue Lake, Ontario. Algonquin will host its annual Winter Activities Day - including quinzee-building - next month.

There is science at play in the creation of these dark and dead-quiet domes. Many quinzee-builders "mulch" snow by trampling it before they begin their mounds, packing as they pile. Heat from the pressure changes the snow crystals' structure, Baker says, and has a binding effect. Snow should set - an hour at least - before digging begins. Sticks should be slid in from the outside to help a digger know when a consistent wall thickness of six inches or so is achieved.

Size is a function of a digger's ambition. A team of about 10 students built a "super quinzee" a couple of years ago, says Jason Carter, a biology teacher at Houghton High School in Michigan, which holds an annual Quinzee Day in February to give 10th-graders a taste of winter-survival tactics. "They were able to fit the whole class of 100 in it," says Mr. Carter, still incredulous. "They worked furiously all day, and they all squeezed in."

Carter says the school learned a valuable lesson when the tradition began a decade ago. It held the event one year on the same day as a volleyball game. "The girls that participated were just wiped out," he recalls. "They lost their game. So [since then] we've always moved it to a day when there are no athletics going on."

Veterans recommend tricks to reduce the rigorous work. Piling snow on top of waterproof duffel bags or even garbage cans can speed hollowing - pull them out through a hole in the side of the quinzee and they leave a cavity. That tactic has drawbacks. A Boy Scout troop from Honeoye Falls, N.Y., describes in a 2003 weblog entry having buried backpacks and a big garbage can too deep in a mound, a move that "sounded good in the planning stage" but that led to a long and difficult extraction - made more urgent because several campers had left their lunches in their backpacks.

Left to harden, a good quinzee can last. Baker has seen them hold up for a month or longer before falling to the elements. "You probably wouldn't want to have to depend on one for your shelter, because you're never sure you're going to have enough snow," he says. "[People] build them because it's fun. It warms you up, and it's something to do."

How to build your own snow hut

Go ahead, make a dome of your own. The following advice is distilled from builders and first-hand experience. The Monitor accepts no responsibility for snow down your back - or any other mishaps. It's wet work.

Mulch the snow by stomping out your site.

Circle your growing pile, adding shovels-full, lightly packing.

Leave a five- or six-foot pile (10 feet across) to set for a couple of hours.

Poke several small sticks in the top and sides of the mound, about six- to eight-inches deep.

Dig from the side near the bottom - in and then up, to minimize cold-air flow. Hollow until you hit the stick ends, and have a friend near the entrance keeping it clear. Smooth the interior walls.

Create one or more three-inch ventilation holes in the dome. (In an oversized quinzee, a larger side chimney for a very small and inefficient twig fire is possible but discouraged because of the possibility of smoke buildup.)

Place a tarp on the quinzee floor (optional) and whistle for the dog - or the kids, who are by now inside watching Nickelodeon.