in my past life as an aviation engineer, i once sat through a seminar analyzing a catastrophic aviation failure. the chances of the event’s occurrence were calculated at ten-to-the-minus-six. in an attempt to help us visualize what ten-to-the-minus-six meant, the instructor asked us to imagine five wooden tinkertoy wheels. one wheel represented weather, one represented pilot error, one represented a first redundancy mechanical failure, one represented a secondary redundancy mechanical failure, etc. in order for the airplane to crash, all five tinkertoy wheels had to fall into perfect alignment simultaneously in such a way that a tinkertoy stick could thread cleanly through all five center holes. hoar frost is not a ten-to-the-minus-six event. maybe it only needs the three tinkertoy wheels of clear sky, proper air temperature, and correct amount of wind to align. but it is rare enough, and welcome enough, that i felt i had to celebrate its appearance this morning by taking my first, and possibly only, still blog photo with an iphone. shhh. don’t tell anyone.

hoar frost

island lake trail, shoreview, minnesota