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btb31
11-22-2006, 01:44 PM
I know someone must have done the experiment. I'm wondering at what temperature spit will freeze before hitting the ground. I've done quite a bit of research on it, and have yet to find a definitive answer, so I'm turning to the experts. I read that a scientist at the south pole tried it at -20 and it didn't work. I personally tried it at around -35 about 10 years ago and found that it froze almost immediately after contact with the ground. I read that Jack London's character in a story about Alaska estimated an ambient temperature of -75 because his spit crackled when it froze a few inches from his lips. I've read that scientists at NOVA thought it would freeze prior to hitting the ground at -50 or colder. I even read a blog who's author claimed that he did it in Illinois when the temp was -72, however according to NOAA the coldest its ever been in Ill is -36, so I had to discard that claim. Can anyone shed some light on this for me? I'd like to know does it bounce like an ice cube, if so how cold does it have to be to do that? Is there an audible "crackling sound" when it freezes in the air? I'd love to hear about the conditions, results, etc...
Thank you!
File Boy

afmrintern
11-22-2006, 03:49 PM
Water does not freeze in air without a nucleus until -40F (or C as they are the same at -40) That's when Ice fog can be observed instead of fog. That being said, BOILING water can flash freeze in the air a bit before that, and I believe that the observers wrote about this effect this past winter. I've tried it both with boiling and cold water at -30 and only the boiling froze before hitting the ground.

Your question is a bit more difficult, as spit is not pure water and impurities will impact the nucleation point. The other thing to take into effect is volume vs rate of cooling. I'd suspect that there is a point, likely below -40, but I have no evidence of what that point is.

Perhaps someone else has had more opertunity than I...

afmrintern
11-22-2006, 03:51 PM
A quick edit, Monday, Feb 27th is the day the crew posted about the boiling water last year, but it's not very descriptive, more visual!

You can see it at this link:
http://www.mountwashington.org/weather/comments/index.php

Bill O
11-22-2006, 04:06 PM
If -40 is the magic number (or about) Mount Washington is not where you want to be directing your questions as it rarely gets that cold on the summit or anywhere else in New England for that matter. Maybe once a decade. The people at the south pole would be much more helpful as it is below -40 for most of the year.

btb31
11-28-2006, 11:21 AM
Its surprising to me that it doesn't get below -40 up on Mount Washington more than once per decade. I was in upstate New York for two years, and we had -35 on one night (and I believe a night of -30 and another of -25). Perhaps that was just a really abnormal cold snap. I just looked up the temperature extremes by state and NH's coldest was -47 (I wonder, was that at Mount Washington?). Vermont's was -50 and surprisingly New Yorks is -52. OK, I'll look elsewhere.
Thanks again!

Bill O
11-28-2006, 06:12 PM
Its surprising to me that it doesn't get below -40 up on Mount Washington more than once per decade. I was in upstate New York for two years, and we had -35 on one night (and I believe a night of -30 and another of -25). Perhaps that was just a really abnormal cold snap. I just looked up the temperature extremes by state and NH's coldest was -47 (I wonder, was that at Mount Washington?). Vermont's was -50 and surprisingly New Yorks is -52. OK, I'll look elsewhere.
Thanks again!

Yes, NH's record low was on the summit of Mount Washington.

My -40F once per decade was a guess, but it seems to be the right order of magnitude. I mean, its not once per year, and its not once per 100 years.

You're right about seeing all those cold temps in upstate NY. The coldest temps (record low type temps) tend be in the valleys.