The first clouds are thin, wispy cirrus, followed by sheets of cirrus and cirrostratus and altostratus.
最开始的云石薄而缥缈的卷云，紧接着是成片的卷层云和高层云。
2
When cirrostratus clouds are disturbed by planes or strong winds, the droplets can freeze instantly or evaporate, the latter of which will form the hole.
当卷层云受到飞机或强风的干扰时，水滴会立即冻结或蒸发，若为蒸发就会形成孔洞。
3
These clouds occur within cirrostratus clouds, which are often composed of ice crystals and drops of water that are below freezing temperature but still in liquid form.