Answer:
When we are on an airplane above the clouds, it can appear as if we're passing each cloud slowly because there is no frame of reference to judge our speed. Our eyes can't detect any movement on the ground, and there are no other objects in the sky to provide a sense of speed or motion. Additionally, clouds are often quite large, so it can take several minutes to pass over one even at high speeds. This can create the illusion that we're moving slowly, even though we're actually traveling at several hundred miles per hour. Our brains are not accustomed to seeing objects at such a high altitude and speed, so it can be difficult to accurately judge our motion relative to the clouds.