ice fog

reesetee Thanks! Wasn't much of a dilemma--I added both. :-) Nov 5, 2007

skipvia Chinooks are definitely seasonal, depending as they do on warm winds from the south replacing the normally cold and dry air over the interior of Alaska. But they're not regular or expected--they just happen sometimes. Ice fog occurs as a function of of the convergence of several conditions--a thermal inversion (warmer air aloft trapping cold air below), no wind, and a build up of moisture which can occur from any source of combustion (e.g., auto exhaust) which freezes and doesn't dissipate.

So--hope this helps a bit with your list dilemma. Nov 5, 2007

reesetee That brings up a good question, skipvia--is a chinook (or for that matter, ice fog) an uncommon event? Sounds as though it's seasonal. I think I was going for unusual weather events on that list, and now I'm wondering whether ice fog fits the bill, too. Still, would be fun to add both. :-) Nov 5, 2007

skipvia Reesetee--you might also want to add chinook to that list. In Alaska, a chinook is a warm, moisture-laden wind out of the south during winter. I've been outside when the temperature has risen from -20 F to +28 F in the space of about an hour due to a chinook. Also sometimes referred to as the pineapple express, since the air mass usually comes from Hawaii, straight up the Gulf of Alaska. Nov 5, 2007

reesetee Sounds lovely--unless you have to navigate through it. I've pinched this for my list of bizarre weather events. :-) Nov 5, 2007

skipvia Frozen fog, essentially. It occurs at temperatures of -20 F or so and can become so thick at colder temperatures that activities are canceled. Quite beautiful if there is a bit of sun illuminating the ice crystals. Very annoying in the dark... Nov 5, 2007