Meteorology Question

[ThomasRH]

Can anyone tell me what is a John wind effect please?
I had done some research and still can't find the answer
Thanks

[TractorBoy]

Do you mean a Fohn wind?

[ETOPS]

Or even Föhn wind :)

Weather Facts: Föhn (foehn) wind - Weather UK - weatheronline.co.uk (http://www.weatheronline.co.uk/reports/wxfacts/The-Foehn-foehn-wind.htm)

[TractorBoy]

I couldn't find the umlaut!

[Pirke]

John shouldn't eat so many beans...

But I think he means Föhn indeed. See wikipedia: Foehn wind - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Foehn_wind)

[ETOPS]

I couldn't find the umlaut!

I keep a few lying about - just in cäse :ok:

[India Four Two]

It's called a Chinook in my current location - very warm and windy, and can arrive very quickly.

In Pincher Creek, the temperature rose by 41°C, from -19 to 22°C, in one hour in 1962.

https://en.wikipedia.org/wiki/Chinook_wind

Snow tends to evaporate rather than melt and it can be very dusty, as the wind picks up the sand used on the roads after snow falls.

The Chinook Arch often develops as a horizon-to-horizon continuous lenticular cloud:

https://upload.wikimedia.org/wikipedia/en/1/10/Chinook-arch.JPG


https://upload.wikimedia.org/wikipedia/commons/thumb/4/42/Chinook-arch-Claresholm.JPG/1300px-Chinook-arch-Claresholm.JPG

PS Brits please note: it's pronounced Shin-ook (as in look) and not Chin-uke (as in Luke), which seems to be preferred "Rupert" pronunciation for helicopters of the same name. ;)

[flyme273]

Concur Fohn Wind seems to fit the question. Can turn a good ski slope to slush in one afternoon.

flyme.

[Steve6443]

The Word Föhn is German for a hairdryer.... so if you imagine that a hairdryer is pumping out hot air, that's what a Föhn wind is.... the airmass is being pushed over the mountains, descending down the other side and gaining temperature as it sinks......

[Steve6443]

S Brits please note: it's pronounced Shin-ook (as in look) and not Chin-uke (as in Luke), which seems to be preferred "Rupert" pronunciation for helicopters of the same name

Ok, agree with you there but then can we also agree that

ALUMINIUM

is pronounced Ahhll-you-mini-um and not ah - loo - min - um

(note there are TWO I's in the spelling of Aluminium).

Thus endeth today's installment of english pronounciations...... :D

[taybird]

Föhn wind:

Background knowledge - "dry air" changes temperature by 3 deg C per 1000', while "saturated air" changes by 1.8 deg C per 1000'. Dry means anything that isn't saturated, so it can still hold lots of water vapour and be considered as dry. Also the temperature changes or Lapse Rates are sometimes given different values in different text books. The main point here is that dry air changes temperature more quickly than saturated air.

1) When air cools, it can reach saturation. As a result, clouds and precipitation is formed. At this point it cools more slowly. (The reason for this is that energy is released when water vapour condenses to create liquid water.)

2) When air moves towards a mountain, it is pushed upwards (orographic lift). When air rises, it cools. So the process in part 1) can occur.

3) When the air reaches the other side of the mountain, it has given up some of its water, so it is drier air.

4) As this drier air descends, it warms up more quickly than it cooled going up the first side, because it is not saturated any more.

So this air moving down the lee side of the mountain is warmer and dryer. It's called a Föhn wind because it is common in the Föhn region.

Note this doesn't always happen. It requires air of the right temperature and humidity to be moved across a mountain range in such a way that orographic lift occurs. The bit that makes the lee side warmer is precipitation on the upper windward side of the mountain.

[paco]

The Chinook is slightly different to a true Fohn wind - on the West side of the Rockies, the air is so dense (from the cold) that it butts up against them and doesn't go over - this means that the air from way up comes directly down and warms up even more as it is likely dry in the first place.

phil

[megan]

is pronounced Ahhll-you-mini-um and not ah - loo - min - um
If you read up on the etymology of the words you'll find that both spellings are correct. British chemist Humphry Davy originally gave it the name alumium, later settling on aluminum. An anonymous contributor to the Quarterly Review, a British political-literary journal, in a review of Davy's book, objected to aluminum and proposed the name aluminium, "for so we shall take the liberty of writing the word, in preference to aluminum, which has a less classical sound."

[India Four Two]

The Chinook is slightly different to a true Fohn wind - on the West side of the Rockies, t

Phil, did you mean the East side?

[7of9]

ALUMINIUM

is pronounced Ahhll-you-mini-um and not ah - loo - min - um

(note there are TWO I's in the spelling of Aluminium).

Ha ha you try educating the Americans that!

I say it as we here say it & they look at me like I'm stupid!

Water = wader
Butter = budder

I keep telling them there are T's in there but they look at me like I'm thick!
Lazy version of English they have, but I love em!!

[paco]

No, the West side, otherwise you wouldn't get the warm air in Calgary :). Last time I was in Okotoks the arch was very clear.

Phil

[India Four Two]

I've spent enough years on both sides of the pond that I just go with the flow in terms of spelling. I even learnt to say zee rather than zed when living in Texas.

Canadian spelling is a mixture of British and American. We write colour and harbour and centre, but on the other hand, tire and as has been pointed out, aluminum.

Incidentally, aluminum is produced by Alcan Aluminium Limited.

[glendalegoon]

one of the fohn winds is the santa anna winds of southern california.

I am surprised that there isn't info about these winds, sometimes called gravity winds available online.

[India Four Two]

I thought the Santa Ana is a katabatic wind, rather than a Föhn wind.