(Dujon) The -34°C is rather mild for Jakutsk in Dec/Jan. The mean is -43°C. There is no wind, or snowfall, but the ground is snow-covered from what fell in Oct/Nov, typically about a foot. The only weather is fog, which can last for a week or more with temperatures down to -51°C, the lowest I've seen in 4 yrs daily monitoring. The short summer is like that of central France and it hardly ever rains. I bet they make the most of it. There is an even colder place, Ojmjakon, where the January mean is -50°C with no weather at all, just brief sunshine while the sun crawls shyly above the horizon for a few hours. Young kids are not allowed out of it goes below -45 because the cold air can damage their lungs. If you were so daft as to put the mouthpiece of a brass instrument to your lips in that degree of cold it would blow more than two semitones flat, the least of your worries, I'd say. Perhaps there's a special short Russian trombone.
What's the science behind that then, Rosie? I would have expected extreme cold weather to reduce the size of the instrument, thus shortening the column of air one needs to vibrate. I would expect this effect to sharpen the instrument.
(Phil) The instrument does get a tiny bit shorter (about 2 mm at -50°C) but the overwhelming effect is the reduction in the speed of sound as the temperature goes down. Since there is a standing wave in the instrument the lower speed causes it to take longer to go down and up the instrument, thus lowering the frequency and therefore the pitch. In effect the instrument becomes longer as far as the standing wave sees it. Of course the player's breath warms it up quite a bit, about halfway beteen ambient and body temperature. Even allowing for this (which I didn't in my original posting), the adjustment is about one inch on the tuning slide for 20 degrees and this is just a bit more than is usually available. So if you're playing outside at 0°C all you could do would be to play "short", as they say. Fortunately I don't do marching bands or Sally Army stuff.
(Darren) That's correct. The whole instrument would be flat and it wouldn't sound wrong but any other instrument accompanying it would have to tune down a bit. Rather difficult with a piano. One way round it would be to have a small bleed of a lighter gas into the air the organ uses. You could use hydrogen, helium, neon, methane, ammonia or hydrogen fluoride. Perhaps I should patent this lunacy.
Wouldn't some of those risk producing the Amazing Exploding Organ? That puts me in mind of the Large Hot Pipe Organ which produces sound by exploding a propane/air mix in its pipes.
(Darren) It's blown itself to pieces and taken the website with it. I drew a blank with your link, alas. Helium would be safe enough and it's much cheaper than it used to be. It would be amusing to use sulphur hexafluoride, totally inert and non-toxic. It would lower the pitch by over an octave. I think I'd better shut up now.