ALEPPO, Syria -- Darkness comes early to the streets of this ancient city, once a symbol of Syria's richly storied past and now at the heart of the deepening nightmare that the country's revolution has become.

By 5 p.m., people are scurrying home, down streets potholed by artillery, past piles of rubble and mountains of garbage that hasn't been collected in months, to spend the evenings huddled in the cold without heat, light or, increasingly, food.

"We just lie under blankets because it is so cold. We have no work, no money and no life," Omar Abu Mohammed, 55, one of the few remaining residents of his badly bombed neighborhood, said as he prepared to head indoors for the night.

"It is time to go now because soon there will be snipers," he added as a shell boomed softly in the distance.

Shells are exploding somewhere in Aleppo most of the time, but after five months of fighting, people have become inured to the ever-present threat. Rain and cloudy skies have deterred warplanes, providing some relief from the airstrikes that can wipe out whole apartment buildings, along with their inhabitants, in an instant.

But the onset of this second winter since Syrians rose up against their government 21 months ago is bringing new calamity to a people already ground down by violence and war. Hunger, cold and disease are emerging as equally profound challenges in the daily struggle that life has become for millions, not only in Aleppo but across Syria, where the quest for greater freedoms sparked by the Arab Spring has gone horribly wrong.

"You can hide from the shelling, but if your child is hungry and there is no bread, what can you do?" asked Abdullah Awuf, 29, a driver who struggles to feed his infant son amid sky-high prices for fuel and food.

Aleppo is not the only place in Syria where conditions are dire. Across the country, reports are emerging of people foraging for food in garbage, stripping buildings for firewood and lining up for hours for scarce bread as the government-run distribution network breaks down.

The United Nations appealed last week for $1.5 billion to help 4.5 million needy Syrians, a record amount for an emergency, said Panos Moumtzis, the regional relief coordinator for the U.N. refugee agency. This one is unfolding almost entirely out of sight because most places are too dangerous or inaccessible for aid workers or journalists to visit.

Most of the relief money, $1 billion, will be spent to help the 500,000 refugees who have fled to neighboring countries. An additional 4 million people inside Syria are in need of food and medical assistance.

But because the government restricts U.N. access to areas controlled by the regime, those in rebel-held territory can expect to see little help.

In the parts of Aleppo under rebel control, the misery is manifest. Fighters with the opposition Free Syrian Army surged into the city in July hoping for a quick victory after ejecting government forces from much of the surrounding countryside. But their offensive was ill-planned and premature, and it quickly stalled, leaving the city carved into a patchwork of front lines across which the two sides shoot and shell each other, along with any civilians in the way.

As the fighting ripples and spreads, the infrastructure that had sustained the city of 3 million is crumbling. Government warplanes target facilities that fall into rebel hands, including hospitals and bakeries. Electricity, which had been intermittent for months, has been cut off since the rebels launched an offensive to capture the main power plant a little more than two weeks ago.

Factories and businesses have ground to a halt. Jobs are almost nonexistent. Fresh meat and produce are available, but at prices far beyond the means of people who haven't worked in months. For many, flat, thin loaves of pita bread, at 10 times the prewar price, are all they can afford. For some, even that is too much.

"On some days, we don't eat at all," said Nadia Labhan, 25, whose husband was killed two months ago by a sniper, leaving her with no means to support her two children. She has joined the growing number of beggars on the street. "It is so difficult," she said, hugging her flimsy robe against the driving wind and rain.