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Weather Singularities
Available only in Astronomical Sun Clock, the web/PWA version. This feature is not available in the other versions of Gordon's Sun Clock.
Some weather patterns are more likely to occur at certain times of year. In meteorology, these recurring seasonal tendencies are sometimes called weather singularities. German examples include the midwinter cold spell, the early-summer cold spell (Schafskälte) and the Christmas thaw. Such patterns do not occur every year, and their timing and strength vary by region.
Sun Clock can check current weather forecasts against regional rule sets, also called mods. A mod defines the geographical area, seasonal periods and weather conditions associated with particular patterns. When a forecast meets the conditions, the app displays the corresponding event with an expandable explanation. This is a rule-based interpretation of forecast data, not a claim that a traditional weather saying must come true.
The German rule set was developed by comparing traditional seasonal weather observations with historical data and deriving testable conditions. The same approach can be used elsewhere, but a pattern that works in one region cannot simply be assumed to apply to another.
On page 2, under section 4 (Functions), the Singularities area shows a matching regional rule set and, when one is detected, the corresponding weather event. Where several regional mods are available, the applicable rule set can be selected. If no rule set covers the location, no rule-set status line is shown.
The PWA evaluates forecasts when it is opened; it does not continuously monitor the weather in the background or send automatic event notifications.
Anyone interested in local meteorology can investigate a traditional weather saying or recurring seasonal pattern, compare it with historical data and develop a rule or rule set for their region. A useful study examines roughly 20+ years, documents the data source and reports how often the proposed pattern actually occurred.
You do not need to programme the app to experiment. Custom rules can run exclusively or alongside the regional catalogue, with matching event keys replacing the catalogue definitions. See Create Your Own Rules for the built-in JSON testing area, the rule-set format, the exact precedence rules and an example prompt for working with an LLM.