Final answer:
The atmosphere limits visible light 'seeing' to approximately 1 arcsecond due to turbulent air cells of different temperatures that constantly bend the path of the light.
Step-by-step explanation:
The atmospheric turbulence limits seeing in visible light to a certain threshold of angular resolution, expressed in arcseconds. This typically limits seeing conditions to approximately 1 arcsecond under average circumstances, although this can vary depending on the local atmospheric conditions and the presence of any adaptive optics systems that may be used to correct for atmospheric distortion.
Air composed of moving cells of different temperatures acts like a refractive lens that bends the path of incoming light, causing the light to constantly change its path before reaching a telescope's detector. This effect is one of the primary reasons why ground-based telescopes cannot resolve images as clearly as space-based telescopes, which operate above the Earth's atmosphere.