Fluffy altocumulus undulatus clouds stain the sky red above a row of trees. These mid-level clouds, which form above 6,500 feet (2,000 meters), often herald an approaching storm.

• 意译：云彩的图片画廊。蓬松的高积云波状云染色天空呈红色在一排树木的上面。这些中云族云彩，形成于地面上6500英尺（2000米），往往预示着暴风雨即将来临。