Did a wind blow in your neighborhood today? Was it a friendly wind, or was it a nuisance? Throughout the world many kinds of wind are forever poking, sweeping, moaning, and changing the weather. One of the least known winds, the foehn [pronounced like fern), does not churn up the seas like a monsoon or hurricane or whirl madly through the flatlands as does a tornado, but shows a weirdness all its own.
The foehn is born when an air mass is blown aloft over a major mountain range. As the warm air mass rises, the moist air expands and cools. A huge wall of clouds is produced on the mountain crest as moisture condenses. Then the air plummets like a roller coaster to the lower elevations on the leeward side of the mountain, changing into a hot wind that is erratic and very dry. Sometimes the humidity drops as much as 80 percent.
Although the foehn may last only a few hours, it can cause great damage. Its downdraft can be crushing and vicious. The temperature shoots up. People who live in mountain towns in its path are alert for possible flash floods and fire. Because its heat softens the snow in the high mountains, avalanches may begin to rumble. The foehn slices through mountain passes at tremendous speeds, going as fast as eighty miles per hour, picking up dirt and rubbish in its troughlike wake. In stark contrast, the air a mile on either side of a foehn’s path is clean and calm.
Regions in which these winds are frequent and severe are called foehn tongues. The Alpine valleys of Austria, Switzerland, and Southern Germany are particularly affected because of the massive mountain chains that crisscross those areas.
Another characteristic of this weird wind is its strange effect on human behavior. Some scientists claim that the electrical balance in the atmosphere is upset when maritime air is transformed into dry, furnacelike gusts and that this change produces foehn sickness. Weather-sensitive people complain that this illness is not only real but disturbing and troublesome.
Schoolteachers everywhere agree that windy days are poor learning days! Children cannot settle down and concentrate. They wander around the classroom, giggle, and whisper even more than usual. In areas where foehns occur, students are more severely affected. They fail exams at an unusually high rate, and in Innsbruck, Austria, a city well acquainted with this wind, school instructors have canceled examinations during a foehn.
Victims of this weird wind often suffer severe headaches, or they are depressed and irritable. Billboards along the highways advertise antifoehn pills. Some people suffer from nervous exhaustion and take medicine for pain and discomfort.
When the foehn blows, tempers run high and brawls are common. In criminal trials the weird wind has even been used as a defense. Doctors often postpone surgery until a foehn has passed. Farmers have blamed the foehn when cows give little or no milk during this windy period.
A teacher from California, who went to Austria to study, made fun of the tales he had heard about the foehn. Years before, he had broken his leg in a skiing accident. When his old wound began to hurt, it was as though the break had just happened, and the pain was agonizing. He soon learned that the weather had changed and that a foehn had descended the mountains into the valley where he was staying. He stopped making fun of the foehn stories.
Autumn and spring are favorite times of the year for the weird wind to occur, but occasionally a foehn will strike even in winter. It may last only a few hours, or it may continue for up to two weeks.
This weird wind does earn a few plus marks. In springtime it melts the snow in high mountains, which allows the cows and sheep to be sent early to Alpine pastures. Some valleys have a higher mean annual temperature, thus allowing fruit trees to bear more than the usual crop.
Foehn-type winds are known throughout the world. In the United States the Santa Ana in southern California is the most infamous wind because of the destructive fires that rage as it whips through the dry mountain brush. Down from the Rockies onto the plains of Wyoming and Montana flows the milder chinook, an Indian word that is said to mean snow eater. In twenty-four hours a chinook can melt and evaporate two feet of snow.
The khamsin is a middle East foehn, while the Vent d’Espagne plagues southern France. The Canterbury is a foehn that annoys New Zealanders. In Chile the pesky foehn is called zonda, and in Sumatra and Java the foehn is known as a bohorok. “Lucky” Greenland has a double foehn, a wind on both its east and west coasts.
Though meteorologists have extensive technical knowledge and sophisticated equipment, weather still plays its tricks. And when it chooses, the weird foehn blows gleefully, alarming and confounding us!