Ice crystal formation (6)
I believe the answer is:
cirrus
(Other definitions for cirrus that I've seen before include "Light wispy clouds" , "Highest form of clouds" , "High, thin cloud" , "Wipsy white cloud" , "Highest form of cloud" .)
I believe the answer is:
cirrus
(Other definitions for cirrus that I've seen before include "Light wispy clouds" , "Highest form of clouds" , "High, thin cloud" , "Wipsy white cloud" , "Highest form of cloud" .)