We've started to get snow in my part of the country and now that my exams are done (might've made the dean's list, how creepy is that?) I am thinking about random things way too often. Mainly things that everyone claims to know but when I start thinking about it I really have no idea why they happen the way they do. A lot of examples of this regard water and what happens when it reaches the freezing point because I have all these nice examples right outside the window. I also like answers to said questions so can someone take a stab at them? Thanks.
1. Seeing your breath when it's cold outside. Seriously now, I can't figure out for the life of me why exactly this happens albeit I know I heard why before. Has something to do with water vapor and temperature change I reckon but I don't know what it is exactly... also does it really disappear after you stand outside awhile or are you just not paying attention?
2. Snowflakes. How many water molecules go into the makings of one snowflake? Why do they arrance themselves in such a way that no two snowflakes are alike? Is there any other component of water that makes it turn into snow or can other compounds become snow as well? (I think I've heard methane does once but am not certain.) Also would snowflakes made of other elements make similar snowflakes (ie it's a universal thing that snow crystals have x properties) or is water special in the type of snowflakes it forms? Obvious temperature differences between the two compounds and their melting points does not really count here.
Ok, that's about it for now. Thanks for listening guys, I just don't like not knowing answers is all.

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Creepy? That's great. =D>
I suspect it's a lot like making fog. The breath coming out of your mouth is going to be around 37C and lets assume its saturated with water vapor (gas) at that temperature. As it hits the cold air and cools, the water vapor will "precipitate" out as extremely tiny water droplets, like fog. I suspect it dissipates because these tiny droplets very quickly evaporate in the relatively dry air.
Lots of websites about snowflake formation
about.com
java interactive
The shapes are basically controlled by the temperature of formation. As the flake moves around in the cloud, the temperature can change and the formation changes with it. So the final shape is subject to the entire thermal history.

Give me the weight of a snowflake and I'll calculate the number of molecules (couldn't Google up a weight).

I don't know about the shape of other compounds snowflakes. But this excellent website about halos and sundogs (optical phenomena caused by ice crystals high in the atmosphere) has imformation about halos on other planets (Mars, Jupiter) caused by the different shapes of the "ice" crystals in their atmospheres (CO2, ammonia).

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Nice site here about snow flakes and ice crystals. Site is easily located via spaceweather.com > Essential Web Links (at the bottom of the home page) > Snow crystals

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

Last week I happened to buy the The Little Book of Snowflakes and enjoyed it before wrapping it as a present. That guy really knows how to capture snowflake images.

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Also look for the book by Wilson "Snowflake" Bentley. I have the Dover edition, and I believe it's still in print. About 2,500 photos of snowflakes. He was the first person to photograph one (in the 1880's I think) and was a pioneer (self-taught!) of photomicrography.

And of course, there is no way to prove (execpt by statistics) that no two flakes are ever the same.

In my opinion, swift is exactly right about both the appearance and disappearence of exhaled breath vapor.

As to how many water molecules in a snowflake-depends on how big it is

Assume, say, 0.1 milligram. Molecular weight of water is 18 grams, which contains 6 X 10^23 water molecules. Works out to roughly 3 x 10^18 molecules. Which is quite a lot of molecules. If a liter of snow contains 1,000,000 snowflakes (just guessing) you would need 10^12 liters of snow to equal the number of molecules in a single flake. This seems to work out to be a cube about 100 meters on a side.

I really wouldn't want to sort through that looking for dupes.

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If they can get you asking the wrong questions, they don't have to worry about the answers.

You really ought to get The Flying Circus of Physics

Snow! I just can't imagine it at the moment - today was 39 celsius in Sydney (102 farenheit).

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Awww, poor paulie jay, no white Christmas in Australia.
It's snowing here right now I'd like to add in that "classic snowfall" way where they're just kinda sticking together and drifting slowly down. The grass is properly covered now, I think my siblings and I will take advantage and go sledding. 8)
And by the way, I'm still mind boggled about how so many water molecules can be so symetrical if that makes any sense.

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Yes, I have a life. It's quite different from yours.

I believe that the no two snowflakes are alike thing has been disproven as I believe a few years ago someone DID find two identical ones.

Just like the ones I've never known...

Just one white Christmas - that's all I ask. Have you ever tried cooking a turkey in mid summer heat...?

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The plural of "anecdote" is not "data".

What did they use for the definition of "identical"?

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Yeah, but have you ever tried to do a barbie at -30C?

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

-12 [Edit: Oops. Should be -23C (-10F). I converted +10F.]

Complete success. That was the coldest of a sequence of winter picnics we did one place I worked.

Baked potatoes make excellent hand warmers.

If you think a hot steak tastes good in the summertime...

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I've certainly barbied/BBQed in the -5 to -10C range. No problem, and I use charcoal (not propane).

paulie jay, if you want to see a white Christmas, you just need to come for a visit here.

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At night the stars put on a show for free (Carole King)

One Earth, One Sky - IYA 2009
All moderation in purple

It's shaping up to be a white Christmas here and the new grill on the new deck at the new house is sure to get a workout this winter. Already has, in fact. We'll just have to see what kind of temp record we can set.