foehn

See also khamsin, mistral, sirocco.

The foehn is an ill wind that brings about negative human behavior. The one foehn that I know in particular is the Santa Ana wind, written about in Joan Didion's essay "Los Angeles Notebook." (much of the following is taken directly from the essay) A foehn is created by a cold mass of air on the leeward slope of a mountain that is warmed as it comes down the mountain and eventually appears as a hot, dry wind. It is proven to cause headaches, nausea, allergies, nervousness, and depression. Indians who felt the Santa Ana used to commit suicide because of the negative feelings that it caused. Also, suicide rates in Switzerland go up whenever a foehn wind blows. In some Swiss cantons the wind is considered a mitigating circumstance for a crime. In LA during a Santa Ana, teachers do not conduct formal classes because the students become unruly. Also, blood does not clot normally during a foehn.

It is caused by a high ratio of positive to negative ions in the air. Physicists debate over whether this is caused by friction or by solar disturbances, but it is known that the ions are there, and that they affect human behavior and physiology.

Also, a magic spell from Star Ocean 2. Castable by Noel and by the final boss, Indalecio (in the Japanese version, Gabriel). It is a fairly powerful spell, and Noel's strongest I think.

A foehn wind is the result of high pressure inland, often enhanced by low pressure over coastal waters.  Cold polar air settles in over the land, such as in the Great Basin area of North America, and begins spreading along the surface, since it is dense.  Guided southward by the Sierra Nevada in the west and the Rocky Mountains to the east, the air mass picks up speed and also heats up due to compression as it flows to the lower altitudes of Southern California, where it is known as the Santa Anas.  The air starts out dry, and as it ascends various minor ranges along the way it tends to lose what moisture it has.  These winds tend to blow for days at a time (3-7 in the case of Santa Anas) because they are being driven by a huge air mass.  Other foehn winds are due to similar mixes of atmoshperic conditions and geography.

The Santa Anas occur in the autumn and winter, when the land is cool relative to the ocean surface.  The high pressure cells would persist for long periods if low pressure systems didn't come barrelling down from the Gulf of Alaska or the mid-Pacific to break them up.  In spring and summer the high is over the water and the low is over the land, since the land is then much warmer than the ocean surface, and the resulting airflow is not noteworthy enough to merit names.

The Santa Ana winds in southern California are Foen winds. Chinook winds are Foen winds. The lee side of the Alps have very strong Foen winds. Foen winds are simply warm dry winds coming off the lee slopes of a mountain range. Warm and dry hardly does justice to foen (pronounced fern winds), however. A foen wind can gain 50 degrees of more (Farenheit) as it rushes down a mountain slope. Considering that most of these winds start out hot and dry on the other side of the mountains, that makes for a very hot, very dry, very strong wind. The Santa Ana's are responsible for fanning the flames of many southern California wildfires. These winds are so hot and so dry that wild land firefighters fear them.

First, some specifics about how Foen winds are formed. Foen winds form when strong warm winds are forced up over a mountain range. These winds are usually forced over the range by an incoming high pressure zone. As the wind, which is already warm, gains altitude, the moisture is lost in the air. Now our wind is warm and very dry. As the wind races down the slope and becomes denser and under more pressure, it heats up tremendously. We now have an extremely hot, dry, strong wind. These winds can blow for days, day and night. For most people, they are just inconvenient and maybe a bit uncomfortable. For firefighters, they are dangerous.

For wild land firefighters, the cooler temperatures and higher humidities that occur after dark are very important. This is when most progress in controlling a fire occurs. If a Foen wind is active at the time, there is little temperature reduction or humidity recovery at night. The strong dry winds also dry out the fuels for the fire, so the fire can spread much faster. A fire driven by Santa Ana winds is almost unstoppable. I remember sitting in fire camp watching a fire spread across a hillside in southern California one year. We were watching fire trucks attempting to outrace the fire. This fire was moving faster than the trucks, and to our horror, we watched the fire overtake and destroy two of the trucks. Luckily the firefighters escaped injury, but it was a powerful demonstration of Foen winds.

Another aspect of the Foen winds that I find interesting is the claim that the winds carry a highly positive charge. Some people claim that positive ions increase aggressiveness and hostility in people, while negative ions do just the opposite. These people claim that during times of Santa Ana activity the crime rate, traffic accidents, and road rage incidents skyrocket. Of course, it could just be the heat.

Foehn (?), n. [G. dial. (Swiss), fr. L. Favonius west wind. Cf. Favonian.] (Meteor.)

(a)

A warm dry wind that often blows in the northern valleys of the Alps, due to the indraught of a storm center passing over Central Europe. The wind, heated by compression in its descent from the mountains, reaches the base, particularly in winter, dry and warm.

(b)

Any similar wind, as the chinook, in other parts of the world.

 

© Webster 1913