Spots Unknown Under the skin of San Francisco

Snow on Mission Street!

This stuff fell from the sky just a few minutes ago and I'm calling it snow.

You think I'm wrong, but try walking up the stairs from 16th/Mission BART while water is cascading back down, stepping carefully over a whitened sidewalk, and checking the wonder on kids' faces - and then pay heed to this "distinction":

Hail and snow are formed by different processes and thus look quite
different, although both are composed of ice.

Snowflakes are composed of single or conglomerated ice
crystals, whereas hail is a ball of ice.

Snowflakes form when an ice crystal grows in very cold air
at the expense of surrounding water vapor.
By the way, there are many other shapes of ice crystals
(platelets, columns, etc.) that can form in a similar way,
but under different atmospheric conditions.

Hail usually starts as a frozen drop of water on a soil or
pollutant particle. The frozen drop is repeatedly carried aloft
and dropped by strong updrafts and down-drafts in a thunderstorm.
As the hailstone rises and falls, super-cooled water droplets
freeze to its surface, enlarging it.

Both snowflakes and hail drop from the clouds where they formed
when they become too heavy for the upward atmospheric motions
in the clouds to support them.

Did I mentioned it snowed on Mission Street just now?