Technical term for 'Chinook wind(s)'...

[AlexisDetroit]

Years ago while skiing in Banff, Canada a retired US Navy pilot explained how air descending down a mountain range warmed the atmosphere so many degrees per thousand feet of descent. I have been trying to remember the scientific term for this phenomenon. I recall it as sounding like "atavarian" or "adavarian" effect. Please advise. Over...

[zlin77]

I think the term is "Dry Adiabatic Lapse Rate", i.e. descending dry air warms more rapidly(3 degrees C. per 1000 ft.) than ascending moist air cools(2 degrees C. per 1000 ft.)
Also known as a FOHN wind , if my fading memory serves me.

[Luftwaffle]

I teach meteorology to commercial pilot students in Canada, only four hundred miles from the Rockies, and I've never heard any terms other than Chinook or Foehn used to describe adiabatic heating here.

[RatherBeFlying]

Katabatic winds come down mountain slopes and tend to be fast.

I believe the chinook mechanism is that the moisture condenses out and releases the heat of evaporation going up over the mountains; so, the air coming down the other side is warmer.

[Luftwaffle]

Zlin & RatherBeFlying together have the mechanism right. The air cools through adiabatic expansion as it rises on the western side of the slope. At first it cools at 3 degrees per thousand feet, but once it has cooled to the dewpoint, water begins to condense, warming the air, (just think of the opposite of evaporative cooling), so that subsequent cooling is only at 1.5 degrees per thousand feet.

When the air sinks down the eastern side of the slope, it has lost its moisture and warms at the dry adiabatic rate (3 degrees/1000') all the way down. It makes a profit, as it were, and ends up warmer than it started.

But Alexis asked for a fancy name, not the mechanism.

[AlexisDetroit]

...as well as the terminology. Thanks for the responses. I'm not a techie, just merely a avionphile.

[Touch'n'oops]

You maybe interested to know that 'Chinook' is a American Indian name, meaning 'Snow Eater'. Obviously this name comes from exactly what it does.
The temperature difference between one side of the mountain and the other can be a as much as 20C!!!

Lufftwaffle has got it right!!!

RatherBeFlying... Katabatic winds are not really related to this phenomenon.

Katabatic Winds is the flow of air at night down a mountain. This occurs typically when a snow covered mountain side cools a 2 meter layer of air. This cooled layer is colder than the surrounding air, so it starts sinking and proceeds down the mountain side. Thus creating the Katabatic winds!!!

[mustafagander]

WRT katabatic winds - the high ground doesn't need to be cold for the effect to happen. In Zimbabwe, where we were at Kariba every morning around 0300 a lovely cool wind would puff in from the direction of Harare, around 3000 ft above Kariba. The lovely cool breeze would be around 30*C!! Very cool after day temps over 45*C!! No aircon either!!

[Tinstaafl]

I know that type of wind as a Foehn wind (sp?).

[Dick Whittingham]

You need to be able to print an umlaut to get the spelling right.

Used to live on Kennedy Road in Hong Kong. Every evening a katabatic wind would drift down from the Peak, come in through the back window and out the front, dropping the temp to a civilised value and signalling the time to open the San Mig and send out for some satay.

Dick W

[Tinstaafl]

Yeah. I tried dotting the vowel but it just left two marks on my PC screen.... ;)

[Bre901]

Dick WhittinghamYou need to be able to print an umlaut to get the spelling right.
Both foehn and föhn are correct, whereas föehn is not

[AlexisDetroit]

I once knew a German woman who had nice umlauts. When I was a teenager in the 1960s I really dug Elke Sommer even though she didn't have any umlauts that I noticed.

The other day while watching Court TV I noticed a female lawyer with nice torts.:O

[Dick Whittingham]

Ah, but the Bre521, there was an aeroplane!.

Dick W

[Bre901]

Shame Vichy sold them to the Luftwaffe, which used them for SAR (Seenotstaffel)

http://membres.lycos.fr/seaplanespages/seaplanes/picts/br_5212.jpg

More information here (http://frenchnavy.free.fr/seaplanes/bizerte/bizerte.htm)

Oops, wrong forum, this belongs to AH&N :O