Astronomy Seeing
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Astronomy Seeing
Astronomy Seeing provides forecasts of sky visibility and atmospheric conditions, supporting astronomers, meteorologists, and other users who rely on clear skies. It is available worldwide free of charge for 3 days, or for 7 days with a point+ subscription.
It visualises:
• Cloud cover in three layers: low (0–4 km), medium (4–8 km), and high (8–15 km).
• Seeing Index 1 and 2, representing atmospheric turbulence effects on visibility.
• Arcsecond values for estimating the smallest observable object size.
• Jet stream speeds and "bad layers" where turbulence disturbs seeing.
• Visible planets with hourly coordinates (azimuth, altitude, RA, DEC).How it works
• Cloud cover values integrate both density and volume; partial coverage across layers may block visibility entirely.
• Seeing indices are independent of cloud cover and focus on turbulence effects.
• Arcsecond values derive from the seeing indices and turbulence layers.
• Jet stream speeds above 35 m/s or below 5 m/s typically reduce seeing quality.
• Bad layers are defined by strong temperature gradients (>0.5K/100m) and indicate turbulence zones.
• Planet visibility takes into account temperature profiles, with hourly coordinates shown on hover.Limitations
• Forecasts do not include fog or very low clouds (see pictocast for fog).
• Local conditions can differ significantly from the forecast due to topography and microclimates.
• Seeing index does not reflect cloud cover: clear skies can still have poor seeing, and vice versa.Best use cases
• Planning astronomical observations in the short term.
• Identifying optimal observing conditions across different altitudes.
• Comparing turbulence effects between regions or nights.Access
Available worldwide free of charge for 3 days. Extended to 7 days with a point+ subscription or via the meteoblue API.
