altostratus cloud
A mid-level, grayish or bluish sheet-like cloud that often covers the whole sky. Compare with 高層雲 (こうそううん), the more technical term.
See also: 高層雲
Altostratus clouds spread across the sky, making the moon look hazy.
Full kanji spelling; 朧 is not a jōyō kanji, so this form is less common.
Compound of おぼろ (hazy, dim) + 雲 (cloud). The exact historical derivation is uncertain, but the word describes the cloud's blurred, veil-like appearance.