What mechanism stabilizes the light from a planet, preventing noticeable flickering?

Answer

Atmospheric disturbances tend to average out across the entire visible disk.

Because light comes from an extended planetary disk, atmospheric disturbances might dim one edge while brightening another, causing the overall perceived brightness and position to remain steady.

What mechanism stabilizes the light from a planet, preventing noticeable flickering?
astronomyplanetsatmospheretwinklingflickering