Thursday, January 31, 2013

The wind blows like a crazy one

I haven’t suspected that the first post in this blog would be about the wind. But it can’t be anything else. It was the first thing I noticed when I opened my eyes today in the morning. 
I heard it.

It’s not an ordinary wind, it’s foehn wind. In Poland we call it halny, in Romania it is vântul mare. Regionally, it is known by different names like föhn in German-speaking regions, sirocco in Italy, puelche in Chile, Chinook in US and Canada, Wuhan in China and many others. It occurs, when the moving air mass encounters a barrier which is a mountain range. Warm moist air rises through the windward slopes, slowly loses its temperature and drops most of its moisture as a rain. Afterwards the air crosses the top of a mountain range, then falls down the leeward slopes reaching very high speeds and warming up very quickly. As a consequence of the different temperature gradient of moist and dry air, the air on the leeward slopes becomes warmer than equivalent elevations on the windward slopes.

Let’s finish with this scientific approach ;) You know, foehn wind influences our life even we are many kilometers from the mountains. I’m in Cracow today, but I exactly know what is going on in the Tatra Mountains as well…the snow melts. It’s not a good news for the ski alpinist, but luckily it hasn’t spoiled my mood today :). By the way, foehn wind also causes unfavorable biometeorological conditions and people become nervous, depressed, even the increased number of suicides is observed. Its influence is noticed among pigs too;)

In XX century the strongest halny ravaged the slopes of the Tatra Mountains in 1968. The wind blew with a speed of 80 m/s (288 km/h = 180 mph)! It destroyed vast area of forests in Tatras, covered later by windthrows and windsnaps.

 Destruction of the Tatra forests in 1968
Another cataclysm called Veľká kalamita (The great disaster), caused by a strong weend, happened in 2004 in Slovakian Tatras. You can still see its consequences on southern slopes of the Tatra Mountains. It was a lunar scene, quite deserted, but in a course of time a new life started marching in.

Calamity in Slovakian Tatras, photo by Andrzej Sliwiński

Halny and phenomena accompanying it - a cumulation of clouds over the mountain ridge and mysterious altocumulus lenticularis and stratocumulus lenticularis clouds preluding the foehn, attracted and still attract artists attention. 
Stanisław Gałek, Foehn wind, 1948
Stanisław Ignacy Witkiewicz Witkacy, Clouds over Giewont while foehn wind, 1902
 Foehn wind, photo by Andrzej Śliwiński

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