The correct option is Always white.
Explanation
Clouds are classified according to their altitude, expanse, density, and transparency. Cirrus clouds are categorized as high-altitude clouds.
- Altitude and Composition: Cirrus clouds form at elevations between 8,000 and 12,000 meters. Due to the freezing temperatures at this altitude, they are composed entirely of ice crystals.
- Appearance: They are thin, detached, and characterized by a fibrous or feathery appearance.
- Color: Because they are thin and made of translucent ice crystals, they do not block sunlight significantly. Therefore, they are always white in color. They lack the density and thickness to appear dark gray or black, colors typically associated with lower, moisture-laden clouds like Nimbostratus.
Key Takeaway: Cirrus clouds are the highest clouds in the troposphere, easily identified by their thin, feathery texture and persistent white color.