Forecast definition
What is seeing?
In astronomy, seeing describes how steady or turbulent the atmosphere is above your observing location. Good seeing means stars and planets appear stable and sharp at higher magnification. Poor seeing means atmospheric turbulence causes shimmer, blur, and detail loss, even if skies look clear.
Why seeing changes night to night
Upper-air turbulence: Fast wind shear at altitude can distort incoming light.
Ground-level heat release: Warm roofs, pavement, and terrain gradients can add local shimmer.
Frontal boundaries: Weather transitions can degrade image stability even before clouds dominate.
Seeing vs transparency
Seeing: Image steadiness and fine-detail stability.
Transparency: Sky clarity and contrast through haze, moisture, or particulates.
You can have clear skies with poor seeing, or stable seeing with mediocre transparency. Both matter for outcomes.
How to use this in practice
For planetary detail and high magnification, prioritize stronger seeing. For wide-field Milky Way views, transparency and darkness may matter more.