Atmospheric extinction evaluates the transparency of the sky. It can be defined as the amount of light from an astronomical object that is scattered or absorbed by the Earth's atmosphere and not

The coherence time (τ 0) is the time lapse that the light crossing the Earth atmosphere maintains a near-constant phase relationship, both temporally and spatially.

The isoplanatic angle (θ 0) is the angle for which the variance of the differences of the phase aberrations suffered by two rays of light passing closely through the atmosphere from different points

Wind speed and direction, wind gust, relative humidity, air temperature, rainfall, insolation, etc.

The sky brightness (SB) is the routine measurement of the night sky brightness in a moonless night. It is a sky quality parameter that allows for identifying possible contaminating sources like

Turbulence is a particular motion of fluids where the kinetic energy breaks the laminar flow. Optical turbulence refers to the effects that this motion has on light. The optical turbulence in the