Crystalline frost
From Glossary of Meteorology
crystalline frost
Hoarfrost that exhibits a relatively simple macroscopic crystalline structure; to be distinguished from amorphous frost.
Crystalline frosts are classified into five forms: 1) needle; 2) featherlike; 3) plate; 4) cup; and 5) dendritic. Such ice forms are typically developed as a result of deposition at temperatures well below 0°C, the degree of supersaturation and temperature controlling the form.
