What is the name for this strange weather phenomenon? See Details Below.

It was a frigid winter morning in St. Paul Minnesota. The temperature had been around 30° below zero F. (-34.44° C.) overnight. The sky was crystal clear and crisp. A beautiful winter sun had already climbed well into it at around 8 AM when I arrived at work, and it had warmed things to a relatively balmy -20° F. (-28.89° C.).

I had noted on the drive in that there had been a heavy frost overnight. Only after pulling into the parking lot and opening the car door did I realize that the white coating covering the blacktop lot was nothing like ordinary frost. Instead, it looked like a paper-thin covering of snow, with distinct crystals like snowflakes giving it depth and texture not seen in frost. More bizarre, the snow was still falling out of a clear blue sky with nary a cloud in sight. You could actually see the crystals seem to pop into existence around 12 to 15 feet up in the air and grow as they fell toward the ground. At around 8 feet up, they stopped growing and just fell to the parking lot as tiny snowflakes.

I’m guessing it happens when the ground gets extremely cold overnight then warmer, more moist air flows in raising the dew point. The relatively cold ground must super-chill air just above ground level below its dew point, and you get something like clear air frost forming.

What did I see? None of my colleagues at work knew what it was. Some were so baffled they had to go look for themselves before they would even believe it was happening. Many of these were native Minnesotans. What did I see? Was it such a rare meteorological phenomenon that it doesn’t even have a proper name?