Recent weather in Massachusetts has brought me to several ponderances (ponderings? ponderoodles?) :
How is it that there can be fog, never mind significant fog, when the air is below freezing? I believe the temperature was 25 F or so. Fog is not water vapor, correct? Rather, it’s fine water droplets suspended in the air, eventually falling and adhering to every available surface.
I remember in “To Build A Fire,” a story I read in the sixth grade, a little fact about when it’s 20 below, Farenheight. If you spit, the saliva will freeze before it hits the ground, emitting a loud crack. At what temperature would a steady stream of urine do the same thing?
In certain areas I’ve been to and vacationed in, the water mains are not buried deeply enough, and rather than expensively dig them new deeper trenches, a constant-spray system is made somewhere to allow water to flow constantly through the pipes. The thing is, from the main road, where the main is buried deep, the water is nice and cozy at 40 degrees Farenheight or so in the depth of winter. In a secluded spot over a hill over an unforested spot, there’s a sprayer of water. It doesn’t spray much, it just keeps htings moving. Here’s the thing, and I suppose it’s not a question, it’s just really cool to take your 4-year-old cousin to go see this - the sprayer starts before the first freeze. The ground there is considerably hydrated, making all sorts of interesting fungi and moss. The first freeze comes and nothing much happens. But as the ground gets colder, it becomes solid and gets a thin covering sheet of ice that melts every day into a big plant-soggy-thing-mud-thing, and refreezes every night. This, of course, kills all the pretty greens and grays and purples (twere not long for this world). Then comes the first day when it doesn’t get warm enough to melt significantly, and the ice starts getting thicker. The area of ground covered by a constant mist from the sprayer is maybe forty feet by twenty feet, like an oval. This looks like a sheet of glass at first, then turns blue and white. I guess layers form from quick-freezing during the night and slow-freezing during the day - like a tree’s rings, only the growth is a day instead of a year. This gets bigger and bigger and bigger, especially when snow starts falling, and now you’ve got a mound that shan’t get any smaller until February. It does nothing but grow for two months now.
I took my little cousin out to see it last January, the “Ice Castle” was thirty feet long and ten feet wide, with a sort of curved shield that formed right in front of the sprayer - any closer, ice can’t form because the water from the source is too warm. And it can’t go fuirther because of shield. Water continues to add to the sides and it’s just amazing.
I have an inkling of an answer to the first question. I remember in chemistry that when water freezes, it gives off some heat. When ice melts, it absorbs heat. This is true for anything (I think), but is especially true for water, which has a large heat capacity AND a large… word… word… I forget, transition-point-energy-requirement? Something like that. So perhaps, this mist, this fog, is composed of millions of drops of water, some freezing at any given moment and their radiated heat absorbed by the neighbors and keeping them liquid. When another one freezes, it might melt a frozen one. This can happen fast becasue the droplets are so small, keeping the whole mass in the air for a long period of time.
Water can be below freezing but still be liquid. It’s called supercooled and it will freeze on contact with an object. I can’t remember why it happens, but it needs the contact with something to trigger the freezing process.
I tested this last winter, when the temperature dropped to nearly -30° here. I tiook a cup of cold water from my refrigerator (+35-40°) water outside, and threw it up in the air. I got soaked when it blew back on me, still very wet and unfrozen. I doubt the story about spit freezing at -20°, and it would take a horrendously low temperature to freeze body-temperature urine to reach the ground.
The first is called ice fog up here - I will have to (grudgingly) admit that I don’t know for sure, but I always assumed they were tiny ice crystals suspended in the air, once they were any distance from the river. We mostly see it in early winter, before the lakes and rivers freeze over. It doesn’t seem to condense on every available surface like tule fog or sea fog, but it does block your vision almost as effectively.
The second is a True Story, kinda. I had the dubious honor of living in a cabin, in a small town in central Yukon when one fine winter, it descended to -72 F. It had been thirty to forty below for a week or so, then it dove down to fifty or sixty below for another week, then finally bottomed out at the above mentioned temperature. It slowly crept back up to about minus sixty for another week, then returned to between thirty and forty below.
I saw the same film I bet, and had to try it. Your spit really can freeze before it hits the ground. However, you got to use little gobs. If you hork a really big lunger, it hits still semi-solid.
Reports from the gentlemen (I have two younger brothers) seemed to indicate that urine starts at too high a temperature and travels at sufficient velocity to be solid before it hits at that temperature. Great clouds of steam ensue. Reports also seemed to indicate that one wouldn’t want to expose such delicate areas to the ambient temperature required to freeze urine solid before it hit.
The ladies declined to participate, having much more skin to have to expose, and fearing that it was indeed cold enough to freeze their butts off.
The company I work for did a project in Alaska (before I worked for them). According to people who were there, if you tossed your coffee outside it would freeze instantly into a cloud of tiny ice coffee crystals and would blow away in the wind, never hitting the ground. I imagine urine would do the same, but you’d probably end up with a case of frostbite in a place where you really don’t want frostbite.
OK… cool water needs something solid to stick to before it can freeze. So these fogs will go away rather quickly if there’s any air movement - they’ll be hitting surfaces all the time and not getting back up again (Grandma Snowdrop!).
Hmm - well, maybe I got my story wrong. Or the number. In any case, in SOME story I’ve read, there’s SOME temperature listed at which a glob of saliva spat from 5.5 feet up will freeze and “crack” before it hits the flat ground.
Another eyewitness report confirming the above. I spent a few years in Alaska in the US military, which gave me the “opportunity” to spend a lot of time living in a tent in the Alaskan interior in the winter. -50 F was fairly common in January/February, and it reached about -80 F a time or two. Nearly everything behaves differently than you are used to in those temperatures. Spit certainly freezes before it hits the ground, as do the dregs of a cup of coffee. Urine seemed to stay liquid all the way down, but freezes immediately thereafter. Your breath can form beautiful little mini-clouds of ice fog
The effect on other liquids (non-bodily fluids) is interesting too. Mercury thermometers are absolutely useless, as they froze way up at -40 F. Standard diesel fuel becomes extremely viscous, nothing at all like the “gasoline-like” fluid it is at room temperature (back in the day we would avoid this problem by burning aviation fuel/JP-4 in our trucks, not strictly allowed).
Ice fog, also mentioned above, also occurred fairly often in the Alaskan interior. Looks pretty much like regular fog, just, well, frozen.
-mok
