Introduction & principle
Pre-computed probability tables compiled from open atmospheric optics archives (Les Cowley's Atmospheric Optics, WMO climatology summaries).
All toolsPopular Science Query
Rare Phenomena Calendar
Lookup historical occurrence probability for halos, coronae, mirages, noctilucent clouds and more.
Live tool
Relative occurrence
32%
Tool advantage
There is no consumer app dedicated to this; sources are scattered across optics enthusiast pages.
Detailed usage guide
- 1Pick a phenomenon from the menu.
- 2Pick a latitude band and a month.
- 3Read the relative probability and best viewing window.
Common problems & FAQ
Why is noctilucent cloud probability zero in summer at the equator?
Noctilucent clouds form near the polar mesopause and are visible only at high latitudes in local summer.
Related tools
Rainbow Formation Probability
Compute the chance of a primary rainbow forming right now from temperature, humidity, and solar altitude.
OpenSun & Moon Angle Calculator
Compute solar altitude, azimuth, and moonlight angle for any place and time.
OpenAtmospheric Transparency Query
Estimate local atmospheric transparency for astronomical and meteorological observation.
Open