Climates

The document

locales: [en, fr]

conditions:
  clear:
    labels: { en: clear skies, fr: ciel dégagé }
    temperature: 2
    next_to: [fair, frost]
  fair:
    labels: { en: fair, fr: beau temps }
  frost:
    labels: { en: hard frost, fr: gelée blanche }
    temperature: -4

seasons:
  summer: { labels: { en: summer, fr: été } }
  winter: { labels: { en: winter, fr: hiver } }

zones:
  highlands:
    labels: { en: highlands, fr: hautes terres }
    persistence: 3
    change: 1d5-3
    seasons:
      summer: { low: 8, high: 22, conditions: { clear: 4, fair: 5 } }
      winter: { low: -12, high: 3, conditions: { clear: 2, fair: 2, frost: 5 } }

An identifier is a lowercase letter, then up to 31 lowercase letters, digits, _ or -. The climates declare 1 to 64 conditions, seasons and zones; a zone has 1 to 16 seasons, in the order of the year, the first being the one a state without a season starts in. The weather tables of all the zones and seasons together hold at most 20 000 moves between conditions (Climates::TRANSITIONS), counted before anything is built: for each condition of a season, one move to each condition it may turn into. Every condition, season and zone has a label in every language; every neighbour, season and condition named is declared. ClimateReader reads a document of at most 1 MiB and names the place of each problem: zones.highlands.seasons.winter.high: -20 is not a whole number from -12 to 80. The same checks run on climates built in PHP from Condition, Season, SeasonalClimate and Zone.

How a day follows from the day before

Each day:

1. the condition stays, with the weight the season gives it times the zone's persistence, or turns into one of its neighbours that the season brings, with the weight the season gives that neighbour. A condition the season does not bring — after the season changed — turns into one of its neighbours the season brings, or, when it has none, into any condition of the season by its weight;
2. the temperature moves by the zone's roll, plus one degree toward its target — the middle of the season's range moved by the new condition — and stays within the range. A temperature out of the range, after the season or the zone changed, comes back toward it by two degrees a day instead.

The neighbours are what keeps the weather continuous: write them as the sky would move — fair to overcast, overcast to drizzle, drizzle to rain, rain to a downpour — and a season's weights say how often each comes. A zone with a high persistence keeps its weather for days; a low one changes it often.

The shipped climates

Climates::default() reads data/climates.yaml, which Climates::file() names, to copy and adapt. Its sixteen conditions — clear skies, fair, hot and muggy, overcast, fog, drizzle, steady rain, downpour, thunderstorm, strong wind, sleet, snowfall, blizzard, hard frost, heatwave and sandstorm — are labelled in English and in French, and its zones are:

They describe climates of a game world, not of a real place: a world of its own declares its own.