Question

High-altitude cirrus clouds are primarily formed from which substance?

A.
ozone molecules
B.
nitrogen compounds
C.
carbon dioxide gas
D.
solid ice crystals

Answer 1

D. Solid Ice Crystals

Step-by-step explanation:

"Cirrus clouds are wispy, curly, or stringy. They are found high in the atmosphere—typically higher than 6,000 meters (20,000 feet)—and are usually made of ice crystals." -National Geographic