Consider the following statements about a cloud form :

1. These are made up of ice crystals rather than droplets of water.
2. They are thin, stringy, white clouds that trail like feathers across the sky.
3. These clouds are formed at very high altitudes-normally between 6000 metres and 10000 metres.

Which one among the following cloud forms is described above?

The description provided matches the characteristics of Cirrus clouds. According to NCERT and standard meteorological classifications:

• Composition: Cirrus clouds are formed at high altitudes (6,000–12,000 metres), where temperatures are freezing, causing them to be composed entirely of ice crystals rather than water droplets.
• Appearance: They are thin, detached, and white, often appearing fibrous or feathery (the name 'Cirrus' is Latin for a lock of hair or a curl).
• Altitudes: They typically reside in the upper troposphere, generally above 6,000 metres.

In contrast, Stratus clouds are low-level horizontal layers; Cumulus clouds are cotton-like with vertical development; and Nimbus clouds are dark, dense, rain-bearing clouds found at lower or middle altitudes.