Question

What type of cloud forms at high altitudes and appears wispy and feathery?

Answer 1

Cirrus clouds

Explanation:

This is a broad answer, since Cirrus actually refers to a "family" of clouds which are specifically: Cirrus, Cirrostratus and Cirrocumulus. However, among these three, Cirrus is the one that appears feathery and wispy. This trait has caused these clouds to be named as "mare's tails". Cirrostratus is superficially similar to Cirrus, but Cirrus clouds tend to be more isolated, while Cirrostratus clouds are basically a bunch of Cirrus clouds that covers a wide area in the sky in an almost a blanket/sheetlike manner.