James Bannister, 38, said that Arnold Harvey saved his life by giving him this tent. (Petula Dvorak/The Washington Post)

The cold here is different. It’s wet.

It’s one thing to be homeless in the crisp, freezing mountain air of Denver, the nine-fingered man from Colorado explained. But living outside in the District is harder.

So last week, when a stranger pulled up to his makeshift camp of cardboard boxes and a ratty blanket covered in stars and gave him a gift, Michael Ford, 59, was thrilled.

“Nicest guy. Just dropped a bunch of tents off. Nice and new,” said Ford, whose right hand was injured while he was working as a janitor in Colorado.

And about 1,500 feet from the Kennedy Center, a tent city grew.

The tent city that a garbage man with a big heart, Arnold Harvey, built near the Kennedy Center. (Petula Dvorak/The Washington Post)

A half-dozen Coleman tents — big ones with lots of poles, the complex kind that start family vacations off with fights — now sit on the grassy medians underneath the roadway spaghetti of Foggy Bottom along the Potomac River.

They’ve been spotted all over town.

A few near E Street. One near Children’s Hospital.

Who is the mystery tent angel?

Perhaps one of the commuters who drive their fancy cars past the longtime homeless encampment every day and are tired of seeing people sleeping under boxes or in the grass?

Nope.

Or maybe a Kennedy Center regular, disturbed by the folks grilling their dinners under a bridge while he heads to the opera?

Nope.

Then it must be someone who lives at the Watergate and sees the camp every day while taking his Pekingese out for a morning walk?

No again.

The tent angel is the garbage man.

Well, the preferred term is “sanitation worker.”

Arnold Harvey, 58, is a veteran who grew up in the worst part of Kansas City, Mo., one of 12 kids. He promised God that if his life got better, he’d help others.

Life did get better for Harvey. He went into the Army, got married, had five kids, got a good job as a Waste Management driver, got a nice home in the suburbs.

But nearly a decade ago, when he spotted rats crawling on the homeless people he saw asleep in the streets along his 2 a.m. route, he knew it was time to live up to that vow.

So now, before he gets on a Waste Management truck to run his D.C. route, he makes the rounds of the encampments across the city, sometimes at 5 a.m., dropping sleeping bags, clothes, shoes and food.

He doesn’t advertise his work or publicize his giving. I had to do some detective work talking to the folks in the tents to find out who their angel was.

He and his wife started a small charity, God’s Connection Transition, to help manage donations. Last year, he was honored by Fortune magazine as a top employee of a Fortune 500 company for the charity work he and his wife do, feeding about 5,000 people a month.

They recently made a deal with his local Costco, in Gaithersburg, to take all the tents that people return and fail to repack well and donate them to the homeless.

“The tents are a new thing, this is a new effort for us,” he said.

“The tents keep them safer and let them sleep better,” he explained. “But we also figured out that when we get someone a tent, everything gets better.”

They get better sleep and are better functioning the next day.

Their belongings don’t get destroyed in the weather.

And most of all, the homeless people are noticed. And helped.

“I guess people don’t always see them sleeping in the grass,” Harvey said. “But you can’t ignore a tent. The last group of tents we gave out in the spring, those people all got housing within a few months.”

James Bannister said the tent saved him on these past few cold nights.

“I just got out of prison, and none of the shelters want me,” Bannister, 38, said.

He was on the subsidized housing waiting list for years. And his number finally came up. When he was locked up. Drug-dealing charges.

“So I had to give that up and get back to the end of the line,” he said. “No one has room for me now that I’m out, so here I am, until something comes through. I was just walking around, roaming the streets. And here comes this man with a tent.”

Twitter: @petulad