virga

noun3

1. •
   A streak of rain or snow that is dissipated in falling and does not reach the ground, commonly appearing descending from a cloud layer.

   • Strong gusts of wind buffeted the train, and ghostly virga of ice followed it through the night. — 2003
2. •
   A type of note used in plainsong notation, having a tail and representing a single tone.
3. •
   A unit of length: a rod, pole or perch (5½ yards); or a unit of area: a square rod, pole or perch.