Wikipedia:Reference desk/Archives/Science/2015 January 30

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January 30

Snow by country

Besides Canada and US and Russia, which other nations received snow for their winter season? Please tell me the names, thanks. — Preceding unsigned comment added by 70.31.17.253 (talk) 02:59, 30 January 2015 (UTC)

Define just what you mean by "received snow for their winter season". ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:16, 30 January 2015 (UTC)

(ec) Would be much easier to list the countries which never have snow. Nearly every country has snow in one part of its territory, at least on one mountain. Lgriot (talk) 03:19, 30 January 2015 (UTC)

Just for example, to back up what Lgriot says, it snows on Mount Kilimanjaro, which is only 3 degrees latitude from the equator. While I wouldn't be so certain as to say it snows in every country on Earth, it is true that it snows at just about any latitude, given the likelihood of finding a high enough elevation there. --Jayron32 04:03, 31 January 2015 (UTC)

Seasons from space

The image at right should help see where snow is common enough to be easily visible from space. Dragons flight (talk) 03:42, 30 January 2015 (UTC)

Seems odd there is so little snow shown south of the equator (other than Antarctica). StuRat (talk) 15:29, 30 January 2015 (UTC)

I suspect this is simply because there is much less land at high southern latitudes than high northern ones. --Trovatore (talk) 15:41, 30 January 2015 (UTC)

Yes, but I would have expected more snow, where there is land, such as South America, which only appears to have snow in the Andes, even in parts quite close to Antarctica. That must be the Patagonian Desert. Perhaps the Q should be reversed: Why aren't there major deserts in the arctic ? StuRat (talk) 17:45, 30 January 2015 (UTC)

The seasonal temperature difference between winter and summer is much more extreme over large land areas than over the oceans. Because they are typically farther from the moderating influence of the ocean, continental interiors in the North experience much larger seasonal temperature variations [1]. By contrast, the bulk of South Africa and Australia only rarely fall below 0 C [2], which limits the formation of snow. Dragons flight (talk) 19:22, 30 January 2015 (UTC)

See also another map showing countries receiving snowfall (with further distinctions) and this user sandbox thingy listing countries (including almost 80 countries without snowfall in modern times). ---Sluzzelin talk 03:52, 30 January 2015 (UTC)

That is quite misleading in relation to Australia. True, snow rarely falls in the capital cities, but there are areas outside where snow is a regular winter occurrence and our snow resorts have a long history. See Category:Ski areas and resorts in Australia. -- Jack of Oz ^{[pleasantries]} 04:26, 31 January 2015 (UTC)

There is little snow in countries south of the equator because most of the world's land is in the Northern Hemisphere, and because most of the world's countries that are in the Southern Hemisphere are tropical or subtropical. Southern countries that do get snow include Argentina, Chile, and New Zealand, and there is high-altitude snow in the mountains of Africa and in the Andes. As to Antarctica (not a country, but for many purposes listed among countries), it doesn't get that much snow either. It is just that snow that falls in Antarctica doesn't melt. I still don't understand the OP's question, but maybe he got his answer. Robert McClenon (talk) 15:53, 30 January 2015 (UTC)

To add to Robert's answer: The amount of snowfall does not simply increase with latitude. The atmospheric circulation is donimated, on the global scale, by three pairs of convection cells. Atmospheric currents in these cells produce heavy rainfall near the equator (a belt of equatorial rainforests around the Earth), flanked by two arid belts - one north of the equator and one south of the equator, around 20-30 degrees latitude (both N and S). Even further from the equator, again, there is a belt of increased rain- and snowfall, mostly around 50-70 degrees latitude (N and S). Finally, the N and S poles get relatively little snowfall. Thus, the most snowfall is expected around 60 degrees latitude, N and S. However, it so happens that there is relatively a lot of landmass between 50 and 70 degrees N, but relatively little landmass between 50 and 70 degrees S, as Trovatore already mentioned. Dr Dima (talk) 19:00, 30 January 2015 (UTC)

Brings up an interesting question — how much snow falls on the ocean? --Trovatore (talk) 20:30, 30 January 2015 (UTC)

Do you count snow that falls on the ice caps ice shelves that aren't over land? For the record marine snow is not helpful in answering your question :) SemanticMantis (talk) 20:51, 30 January 2015 (UTC)

FWIW, Stanley, Falkland Islands / Islas Malvinas (51°41′S 57°51′W) receives 608 mm of precipitation a year, which is pretty average for a temperate climate (from google: Paris 585, Moscow 689, St Petersburg 633, etc.); however, prevailing winds there (in Stanley) are from the west, so it is covered to some extent by the rain-shadow of the South American mainland. Kerguelen, which is far from any mainland, receives 709 mm. I do not know how much of it is rain and how much of it is snow, however. 65.50.240.210 (talk) 22:36, 30 January 2015 (UTC)

"Snow does fall, but it is temporary and does not settle for long" (from Climate of the Falkland Islands). In reference to StuRat's queries about snow in the Southern Hemisphere, Stanley is only as far south as London is north (both 51°); we had no snow at all in London last year and only a few flurries so far this winter. The southernmost city in the world is Punta Arenas (53°S) in Chile, which is on a par with Dublin or Hamburg, both 53°N. Alansplodge (talk) 02:47, 31 January 2015 (UTC)

It should be noted that latitude alone is not enough to determine climate. Boston is at 42^oN, and very snowy. Prevailing wind patterns and locations of major landforms and ocean currents have a LOT more to do with climate than latitude alone. --Jayron32 04:00, 31 January 2015 (UTC)

Ideal computation

Considering Landauer's principle is a function of temperature, and assuming we wanted to put in the energy to cool a computer asymptotically down to absolute zero, would it be possible to achieve exponentially higher rates of computation as the working temperature approaches absolute zero (and thus make the energy spent cooling worth the effort)? Would Bremermann's limit be the sole limiting factor in this case? Googol30 (talk) 04:57, 30 January 2015 (UTC)

Suppose you keep boosting the operating frequency to achieve more calculations per unit time. Long before you hit these thermodynamic limitations, you will find that you cannot build a switch - let alone a complex array of interconnected switches connected as logic gates that reliably operate as a digital computer. To analyze the performance of a switch, you need to study its gain–bandwidth product, which can be considered a limitation derived from first principles of physics. Nimur (talk) 07:28, 30 January 2015 (UTC)

The layout of the cpu would be fixed, too, and you'd run into a limit due to the length of the lines and the speed of light. - ¡Ouch! (^{hurt me} / _{more pain}) 07:20, 3 February 2015 (UTC)

Sublimation?

Sometimes I drop an ice cube on the carpet in a warm (21C) room. I leave it there and it finally disappears. The carpet is not wet. Isnt that sublime?--86.190.191.233 (talk) 19:18, 30 January 2015 (UTC)

Not enough information. The carpet may wick away the moisture so efficiently that it does not feel wet. Also, the relative humidity in your climes is unlikely to be dry enough for sublimation at those temperatures. Try doing it on a plate on the floor.--Aspro (talk) 20:24, 30 January 2015 (UTC)

Sublimation means it goes directly from frozen to vapor, without ever becoming liquid. I'd bet that if you looked at the spot 10 minutes after the ice cube was dropped, you would find it was quite wet. So, you have melting followed by evaporation, as opposed to sublimation. StuRat (talk) 21:19, 30 January 2015 (UTC)

See Water_(data_page)#Phase_diagram. Sublimation cannot occur meaningfully above 0^oC at room pressure. Ice will slowly sublime below freezing in a process akin to below-boiling evaporation (of the course of many days or months) however, above 0, it will melt first. --Jayron32 03:54, 31 January 2015 (UTC)

Only partially because the ice cube sublimates constantly but also melts and the meltwater evaporates. If you did it in your freezer with has a temperature of -20°C and the ice cube disappears, then you can say that it sublimated. But on 21°C it melts for the most part before it evaporates and just a very little part of the cube sublimates.--Calviin 19 (talk) 11:23, 31 January 2015 (UTC)

And the sublimation is many times slower than the melting process.--Calviin 19 (talk) 11:28, 31 January 2015 (UTC)

When I said "of the course of many days or months" I am sorry that was unclear. What I meant by that was "of the course of many days or months". I hope that clears things up. --Jayron32 21:07, 31 January 2015 (UTC)

Was no over intended anywhere there? Nil Einne (talk) 23:12, 31 January 2015 (UTC)

It must have been an ofsight on Jayron's part. :-) StuRat (talk) 20:59, 1 February 2015 (UTC)