Astronomical seeing refers to the ability to view celestial objects through the obscurations of the earth's atmosphere. These obscurations include opacity, scattering, turbulence, atmospheric and thermal emission, and ionization.

Opacity refers to the fact that Earth's atmosphere is transparent only to relatively narrow wavelength ranges of light. These include visual light, the near infrared, microwaves and radio waves with wavelengths between about 0.35 mm and 1 m. The atmosphere is almost completely opaque to ultraviolet light, x rays, gamma rays, and radio waves with wavelengths greater than 1 m. The need to observe heavenly bodies outside of these narrow wavelength windows, along with the desirability to avoid the degrading affects of the atmosphere are among the main reasons for the development of space-based telescopes.

Ultraviolet photons are absorbed by electron transitions in oxygen and ozone atoms in the upper atmosphere. Because the amount of ozone varies greatly with location and seasonal...