Why Cold Air Smells Different
Pine needles. Wood smoke. Snow. These are the smells of winter, and for people who live with distinct seasons, wintry weather brings its own set of olfactory experiences.
But why does the cold of winter smell different from the heat of summer?
One reason is that odor molecules move much more slowly as the air temperature drops, said Pamela Dalton, an olfactory scientist at the Monell Chemical Senses Center in Philadelphia. That means that there are simply fewer smells to smell on a cold, crisp day than there are on a hot and humid one.
It's the same reason why hot soup smells more than cold soup does and why the garbage truck leaves behind the strongest odors on steamy summer days.
What's more, our noses don't work quite as well when the ambient air is cold, Dalton said. In experiments that require biopsies of olfactory receptors that lie deep inside the nose, researchers at Monell have discovered that the receptors "bury themselves a little more deeply in the nose in winter," she said, possibly as a protective response against cold, dry air.
"We're not as sensitive to odors in winter," she added. "And odors aren't as available to be smelled."
Cold air also stimulates the irritant-sensitive trigeminal nerve, said Alan Hirsch, a neurologist and psychiatrist in Chicago. The trigeminal nerve is what makes you cry when you chop an onion and delivers a hit of spiciness when you inhale a whiff of strong mint.
When odors stimulate both the trigeminal nerve and the olfactory nerve, the experience of smell becomes more intense.
There is a strong psychological component to our sense of smell, Hirsch added, and what we expect to smell has a big influence on what we actually smell.
In "The Invalid's Story" by Mark Twain, for example, a man is stuck on a train next to what he thinks is a rotting corpse but is actually a box of stinky cheese. So overwhelmed by the smell, he spends too long seeking fresh air on the freezing platform and develops a fever that ends up killing him.
"What you think a smell will be impacts whether you like it and what you perceive it to be," Hirsch said. "So, if you go outside in the winter and you are used to smelling snow or chestnuts in the fire or whatever you happen to smell outside, that's what you will interpret smells to be."
Of course, the smells that are available to be smelled differ as the seasons change. Summer brings flowers and dirt and barbeque smoke. In the most wintery of places, there isn't much outside on cold days except snow, blustery wind and cars warming up.
To cope with the smell deprivation of winter, many people compensate by burning more scented candles, cooking more aromatic stews and baking more cookies. That creates a greater contrast between the indoor and outdoor environments.
"You probably have an uptick of indoor scents in the winter," Dalton said. "Homes are closed up, windows are closed. We concentrate the smells of cooking and living."
VIEW PHOTOS: The Stinkiest Places on Earth
Keren Su, Corbis
May 17, 2012
-- Vacation often means visits to pristine beaches and idyllic pastoral retreats. For a masochistic twist, tour some of nature’s most putrid, pungent places, nasty-to-the-nostrils nooks, and foul, fetid funky towns. First stop, Seal Island, South Africa. Start with 60,000 seals plus their poop. Add rotting left-over fish and Seal Island equals one pungent smell. Sea captains and fishermen usually keep their boats upwind of the island, but sometimes a change in the winds can bring the overpowering aroma to the nostrils of seafarers and tourists. Tourists brave the stench in order to see not just the pooping pinipeds, but also the great white sharks that feed on them. Sharks in the area are famous for attacking the seals from below. The great whites frequently launch themselves out of the water with the squirming seals clenched in its jaws. The airborne sharks are poster boy predators for the Discovery Channel’s Shark Week.
Champagne Pool at Wai-O-Tapu Thermal Wonderla
Rotorua, New Zealand If Guns’n’Roses ever tours Rotorua, New Zealand, they'd sing, “Take me down to the Sulfur City, where the air is smelly and the geysers are pretty.” Rotorua was built atop highly active geothermal vents that constantly belch the rotten-egg scent of sulfur, so much so that the town’s nickname is Sulfur City. Just like Seal Island, the stench doesn’t staunch the flow of tourists. Numerous hot springs, geysers and other natural wonders can make a visitor forget that the area smells like an Easter egg that wasn’t found until Christmas. Tourists get a free souvenir as well. The smell sticks to clothes, so even after they leave, the scent of brimstone follows them. Unfortunately for Rotorua’s residents and visitors, eau-de-expired-eggs will never be a chic perfume. The gas can be more than just an annoyance. Over the years at least 10 deaths have been attributed to the hydrogen sulfide leaking from beneath Rotorua. In September of 1987, newlyweds died during the night in their hotel room. A faulty water trap in the unit's shower let gas into their room. An Austrian actress died in a hotel room in February 2000, and some linked her death to gas exposure. The gas might not kill a person outright, but long-term exposure may be a health hazard. The New Zealand Herald reported that hospital admissions for asthma and other breathing diseases in six Rotorua districts were five to 10 times the local average between 1991 and 2001.
Kawah Ijen Sulfur Mine (Andri Tambunan, Corbi
Ijen Volcano, Java Another sulfurous stink spot, a geological vent in Ijen Volcano’s crater, expels volcanic gases rich in sulfur. Move over Mike Rowe of “Dirty Jobs,” the volcano is the site of a job straight out of Dante’s Inferno. First, ceramic tubes condense the sulfurous gas from the vent. Then miners chip off chunks of the yellow material and carry it by hand in flimsy baskets out of the steep crater. All the while acrid clouds of brimstone waft around them. Each load weighs 75 kg (170 lb.) to 90 kg (200 lb.). The workers have to carry their foul cargo about 3 kilometers (1.86 miles) to a sugar refinery if they want to be paid. The miners take home only $5.50 - $8.30 per load and make two trips per day.
US Botanic Garden, Wikimedia Commons
Corpse Flower Habitat, Sumatra The flower Amorphophallus titanum is nasty in name and smell. The scientific name means "giant misshapen penis," which caused David Attenborough to coin the more modest name, “titan arum,” for use in a documentary. A corpse flower by any other name would still smell as repugnant. Not only is the Amorphophallus moniker and appearance rated R, it smells like Hannibal Lector’s leftovers. The flower relies on carrion flies for pollination; hence it produces a fragrance redolent of rotting flesh in order to draw in the flies. Amorphophallus isn’t the only stink blossom in Sumatra. Rafflesia arnoldii, the world’s largest individual flower, can be up to three feet across and earned the nickname “corpse flower” for the same reason as its neighbor Amorphophallus. In fact there are over 30 species of plant in Southeast Asia that use the smell of death to attract pollinators. In Sumatra, perhaps you shouldn’t bring your date the local flowers, unless you are also wearing eau-de-expired-eggs cologne from your trip to Rotorua.
PHOTOS: Flowers To Die For
Yun Huang Yong, Wikimedia Commons
Durian Fruit Orchard, Southeast Asia Southeast Asia is home to another pungent plant, the durian fruit. Millions relish the durian, but to the uninitiated the foul fragrance of the fruit brings to mind rotten onions, turpentine and gym socks. The smell was almost enough to stop 19th-century naturalist Alfred Russell Wallace from tasting the fruit, "but in Borneo I found a ripe fruit on the ground, and, eating it out of doors, I at once became a confirmed Durian eater," he wrote in his book about the Malay archipelago. Durians may be considered the “king of fruits” by some, but the king has to ride in his own carriage. Some places, such as Singapore, have banned the fruit from public transit. The forbidden fruit may not be welcome on the bus, but it is welcomed into a wide variety of desserts, candies and even ice cream.
Gerhard Egger, Corbis
Hereford, Texas Cheese is the tastiest of stinky things that come from cows. Manure, on the other hand, is not too yummy on a cracker. Hereford, Texas claims to have highest concentration of cattle in the world. More than 3.5 million meat and dairy cows can be found within a 100-mile radius of the city. Approximately 800,000 of them are within just 20 miles of downtown Hereford. Every single one of them adds its own pungent plops to the manure mix. Only 14,600 people call Hereford home, which means there are about 241 cows for every human living in town. The region’s economy is based on cattle, so to the locals the smell of manure is also the smell of money. The smell of both manure and money are threatened in Hereford. The past few years of severe drought shriveled the cattle’s pastures and caused the price of pumping water to skyrocket, reported the Irish Farmers Journal.
St. Helen Auckland, England If cattle smell bad, what about cattle fed on onions? The folks in St. Helen Auckland in northeast England cried about un-a-peeling odors emanating from West Musgrave Farm. The farm’s owner, Tony Shepherd, had been feeding the onions to his cattle. Rotting onions could be smelled up to a mile away, residents of the village told the Northern Echo. Living next door was enough to make their eyes burn and cause breathing difficulties. More than 200 people signed a anti-onion petition, while others formed a Facebook group calling for an end to the acrid scent. Shepherd was forced to stop using onions as cattle feed in 2011 after the local government issued an abatement order.
Lemnos, Greece People have been stigmatizing stink since the days when Socrates wore smelly sandals. In the ancient world, the Greek island of Lemnos had a funk of mythical proportions. According to legend, Aphrodite had cursed the women of Lemnos with an intensely foul stench because they had neglected her temples. The odor was so bad that their husbands avoided their wives’ beds. Instead the men laid with women stolen from Thrace and enslaved to the Lemnians. This so enraged the Lemnian women that they organized the wholesale slaughter of every man on the island on a single night. The real reason for the smell on Lemnos may have had less to do with an angry goddess than with a sea snail. Lemnos was recorded in antiquity as a site where murex, an intense purple dye, was produced. The dye had to be extracted from a sea snail and processed using human urine. Women working in the dye production industry were cursed with a stench likened to garlic, rotting fish and bromine. A Washington University archaeologist found she had to wear a mask to stand the stench when she re-created murex. The foul odor and deep purple coloration stayed on her for weeks afterward, even after scrubbing with detergent. Like cattle ranches in Hereford, Texas and sulfur mines in the Ijen volcano, the smell of making money was intensely foul on the Isle of Lemnos.
PHOTOS: Alarming Images of Oil-Drenched Gulf