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.

虽然层状云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，但这种不稳定性在云的底部更为不寻常。