High clouds are primarily made up of what substance?

High clouds, which are typically found at altitudes above 20,000 feet, are primarily composed of ice crystals rather than water droplets. This is due to the low temperatures prevalent at these altitudes, which cause the water vapor to freeze into tiny ice particles. The formation of these ice crystals gives high clouds their characteristic appearance, often resulting in thin, wispy structures known as cirrus clouds.

In contrast, water droplets or liquid water are more common in lower altitude clouds. Snow and frost, while related forms of frozen water, are not the primary constituents of high clouds. Snow refers to larger ice crystals that form and fall to the ground, while frost forms at ground level under specific temperature conditions and does not represent the composition of clouds at higher altitudes. Therefore, ice is indeed the correct material that defines the composition of high clouds.