Polka-dotted ice? What?

Well, there is something new under the sun - or under the clouds.

The concept of "wintery mix" (or is it "wintry mix"?) was a clever invention. They didn't have that when I was a kid. The old guy at the equipment rental place this morning said: "That way they've got it all covered."

And in fact, on my way there I began under a lovely downfall of big fat winter-wonderland flakes of snow, already half an inch of them on the ground, and proceeded through sleet, hail, rain, and snow again before I got to the Rent-All place.

And now this! What makes polka-dotted ice form?

The first picture is the balcony outside my bedroom, the second is the porch outside the kitchen.