Star clear
The meteorological designation of a night sky with no or only light cloud cover is star- clear , so that the starry sky becomes visible.
The astronomers differentiate between further criteria:
- Transparency of the atmosphere (usually on a scale from 1 to 5)
- Limiting magnitude (the faintest freely visible stars)
- Air turbulence (turbulence in the troposphere) and its effects as scintillation (twinkling of the stars) or as seeing (movement of the star points in the telescope)
- Disruption from moonlight and urban light pollution .
See also