All that beautiful crystaline speckled snow out there, here's something we probably already knew: It's ALIVE! No, seriously ...

Scientists have long known that the ice crystals in clouds which become rain or snow need to cling to some kind of particle, called ice nucleators, in order to form in temperatures above minus 40 degrees Celsius.
But they did not realize, until now, that the most active particles involved in this process are living ones, Christner said.
"Every snow and ice sample we've looked at, we found biological ice nucleators ... Here's a component that has been completely ignored to date."
[ Rain, snow forms with aid of living organisms ]

Not all of it, but pretty near most of it gathers around bits of kicked-up biology floating above our heads, dewing their own private micro-superhighway express track back down to Earth, and it works like this: Once the airborne temperature dips below -10C, mineral seeds like dust and soot can take over the job, but when you get above that in the warmer winter flurries and all through the spring and summer rains, its critters, teeny itty bitty little critters, but critters nonetheless.

So shovel lovingly ;)