We all have our thermometers to bear. Now that the polar vortex is back and it’s more Mid-Antarctic than Mid-Atlantic around here, Washingtonians — not a Nordic people — are being tested.

Some — the hatless walkers, the bike commuters — embrace the chill. It’s “bracing.” You feel “alive.” Others — the bundled scurriers — avoid it at all costs. It “hurts.” You feel “frozen to death.”

Things get weird in extreme cold, and the week’s temperatures promise to be extreme in the extreme. Weather records, pipes and lips were quickly cracked by the coldest blast to hit the region in decades. Materials behave differently down near zero degrees (please, do not try the trick of throwing boiling water up to watch the ice crystals fall), and so do people. Dogs won’t go out, eyes water, fingers fumble.

“I can’t turn them with my gloves, but I can’t feel my fingers if I take them off,” bemoaned Edward Alvarez on Thursday as he tried to change a tire in Northwest Washington. He was a picture of winter misery, kneeling on a brittle mountain range of slush, hating life and lug nuts. “It makes me want spring to get here.”

And Friday promised a deeper plunge, with lows expected to range from minus-2 to plus-7 across the region. Public schools began announcing delays and closures, unwilling to send students out into the historic chill.

Driver Jackie Myers of Frederick performs a pre-dawn check of her vehicle at a Montgomery County school-bus depot. (J. Lawler Duggan/For The Washington Post)

On Thursday, nowhere did the polar vortex bite more bitterly than the Montgomery County Public Schools transportation depot in Rockville. There is cold, and then there is 11 degrees at 4 a.m. with 400 icy school buses that don’t want to start.

“This is the worst job in our department, bar none,” Todd Watkins said. The school system’s head of transportation blew on his hands as the beleaguered members of the emergency “cold starting teams” wrestled with one balky vehicle after another.

Diesel buses, like the children they carry, don’t like waking up on the coldest mornings. That’s when Watkins calls in the cold starters, teams that arrive in the middle of the night to force the issue. (Some school systems actually leave their fleets running all night in the frostiest weather.) One by one they crank the reluctant engines. For the worst cases — about 25 buses on Thursday — technicians pull up with a Start-All generator and cans of ether.

“Sometimes it takes 20 minutes to get one going,” team leader Giannina Clary said over the whir-whir-whir-whir of a stubborn patient. She is a veteran bus driver on normal days, but on freezing ones, she is a diesel first-responder. “The colder it is, the worse it is.”

Then, after a cough and a roar, Clary sees a thumbs up emerge from the rear of the bus, where her triumphant partner, Cesar Vinueza, is engulfed in a cloud of exhaust.

“We have to do it,” Watkins said as the depot — one of five in the county housing a total of almost 1,300 buses — slowly comes alive with chugging engines and flashing strobes. “If we lose even 10 percent of the buses, there would be chaos in the system.”

Four hours later and 20 miles away, Takoma Park fifth-grader Evelyn Owen-Sharratt was waiting for one of those buses, huddled like an emperor penguin in a clot of bundled school kids. Cold mornings are one of the times she is glad to see the ride coming down the street.

Teams had to brave the cold early to get some stubborn buses up and running at the Montgomery County school bus depot in Rockville. (J. Lawler Duggan/For The Washington Post)

“At least the bus is warm,” she said from deep inside her hood as she climbed the steps.

The polar vortex was bad enough last winter, when a weather threat we’d never heard of struck like an unknown super-villain. Now a second year of vortexes behaving badly leaves citizens to wonder whether ­single-digit days will be a regular feature of the local winter.

Climatically, Washingtonians identify more with New Orleans than Fargo. We know how to handle a swampy August (complain, then leave). But a bitter February?

“It’s okay with me. I’ve ridden in temperatures as low as negative 20,” said Philip Yoo, 31, one of the bicycling die-hards who have made the District a two-wheel city even on days when other commuters limit their outside exposure to the eye slits of their balaclavas.

The minus-20 day was in Michigan, not the District, but Yoo has never let winter deter him from his daily round trip from Mount Pleasant to his ­federal-agency job in L’Enfant Plaza. He was away for the massive snows of 2010 but has friends who drove screws out through their tires and made it around on “ice bikes.”

“It can be a little unpleasant, but it’s a great workout,” he said.

To others, the appearance of alien weather feels like a trick. Maybe a dirty trick. This particular air mass is not just a polar vortex, but one that started in Russia as a “Siberian express.” A whiff of gulag? The return of the Cold War?

“The standard response to questions about the Cold War from my government is that there is no Cold War now,” said Andrei Sitov, the Washington bureau chief of the official Russian news agency Itar-Tass. “There is no ideological confrontation.”

But he did have this warning for Washingtonians:

“Dress in layers.”