While stratiform clouds  often have what is known as Kelvin-Helmholtz instability at the top, an instability that  comes from a velocity shear within fluids, this instability is more unusual at the base of clouds.

虽然层的顶部通常存在所谓的开尔文-亥姆霍兹不稳定性，这种不稳定性来自于流体内的速度剪切，这种不稳定性在的底部更为不寻常。

Now, Asperitas clouds are  thought to be mostly a supplementary feature of stratiform clouds, which are low elevation  layered clouds without vertical development, although asperitas have also been observed to  be stratocumulus or altocumulus.

现在， 阿斯佩里塔被认为主要层的补充特征，层低海拔层， 没有垂直发展，尽管阿斯佩里塔也被观察到层积或高积。

Interestingly, while the bases of stratiform clouds  are generally flat, they tend to develop significant features at the top due to wind and  temperature changes.

有趣的， 虽然层的底部通常平坦的，由于风和温度的变化， 它们往往会在顶部形成明显的特征。