To become hazy or misty; to have reduced visibility because of mist (also used figuratively for things becoming unclear).
朝、川沿いは靄がかかっていて視界が悪かった。
In the morning, the riverside was misty and visibility was poor.
古い写真には微かに靄がかかって見える。
The old photograph looks faintly hazy.
彼の説明には靄がかかっていて、要点が分かりにくかった。
His explanation was vague, and it was hard to understand the main points.