How does Earth’s atmosphere blur images from ground-based telescopes?

Earth’s atmosphere blurs images from ground-based telescopes primarily due to atmospheric turbulence, a phenomenon known in astronomy as "seeing".1

Turbulence creates unstable regions of varying air densities within the atmosphere. These regions prevent light from celestial objects from passing through in a straight, uniform beam. Instead, the light is shifted in a rapid, random fashion, causing the image to flutter or dance. In smaller telescopes, this manifests as a dancing image, while in larger telescopes, the distortions are magnified, resulting in a diffuse, blurred appearance.1

This turbulence effectively limits the practical resolution of ground-based telescopes to about one arc second, regardless of their theoretical capabilities. To mitigate these effects, astronomers use adaptive optics, a system that rapidly adjusts the telescope's mirror surface to compensate for the atmospheric distortions in real time. Additionally, observatories are often strategically placed at high altitudes or in locations with low humidity to minimize these atmospheric interferences.23