Probably most people consider the greenhouse effect as an important, yet subtle, effect on our climate. I suspect though that very few consider it the major effect on our daily weather, amenable to direct sensation, that it really is. Perhaps this lack of appreciation can be partly alleviated with a simple and quick demonstration. Below is my attempt at such a demonstration. This demo focuses on a…
As I've seen it, the three most common ways to depict coldness in art and culture are the snow crystal, the icicle, and the curving frost on windows. All of these have seen relatively little study, but without question the last has received the least. Indeed, I know of only three studies dedicated mainly to curving frost, and all three are over 50 years old. It is perhaps little known that in…
In part 1 (1), motivated by an avalanche story, we saw that avalanching snow would hardly increase its temperature from all the tumbling. In fact, it would, in falling down some elevation X, warm up by an amount that would be about half of that of the increase in local air temperature at the lower elevation. So, in a sense, you might even argue that the avalanching snow has cooled relative to the…
They condense from the vapor, get jiggled and jostled, coalesce, and then suddenly, they freeze. You can see a few strands, more nearly vertical, that must have had a drop slide down soon before freezing, sweeping out all the other droplets and leaving only a thread of densely packed tiny drops. The freezing, one started, likely spreads along a thin film on the web from drop to drop, freezing all…
[This is the seventh and last in the series of re-posted articles, from 2012.] You don’t have to look at frosted surfaces for very long before coming across something like the following. The picture shows a large ice crystal amid a roughly uniform sea of tiny frozen droplets. Between the large crystal and the frozen droplets lies a clear ice-free zone, a dry moat around an island of ice. Sometime…
[This is the sixth in the series of re-posted articles, from 2011.] Why do so many snow crystals look about the same when rotated by 1/6 of a turn? What’s the origin of the six-fold symmetry? Why not five or seven, as Kepler asked(1)? Since it always happens, when it begins to snow, that the first particles of snow adopt the shape of small, six-cornered stars, there must be a particular cause; for…
A recent article in the local newspaper asks the question "Why does snow glow blue?" The author gave one inspiration for the article as "..the way white snow glows turquoise in the holes left by boots or ski poles..." The explanation given in the article is the same as that you can find elsewhere on the internet, and certainly applies to glacial ice: absorption of the red end of the solar spectrum…
Why does snow seem to harden after an avalanche? Those unfortunate few who have been buried in an avalanche often observe the snow, once stopped, has hardened. Some liken it to concrete. Whereas the powder before the avalanche seemed light and easy to move, once buried, the victim finds it impossible to move. I have never had that experience, though I find the observation reasonable. For example,…