# Weather-terms glossary. Each entry: slug, term (display name), short (one-line # definition), body (full HTML; {base} is replaced with the app base path at load # time). Consumed by backend/web/content_loader.py -- see docs/README.md. terms: - slug: climate-normal term: Climate normal short: The typical value of a weather metric for a place and time of year, averaged over decades. body: |- A climate normal is the long-term average of a weather variable (say, the daily high) for a specific place and time of year. Thermograph builds each day's normal from every historical day within ±7 days of that day-of-year, across ~45 years, so a day is judged against its own season, not a single annual average. - slug: percentile term: Percentile short: 'Where a value ranks within a distribution: the 90th percentile is warmer than 90% of days.' body: |- A percentile says where a value falls within a range of past values. If today's high is at the 97th percentile, only about 3% of comparable days in this location's history were warmer. Thermograph grades every day by its percentile against the local ±7-day seasonal distribution. - slug: temperature-anomaly term: Temperature anomaly short: 'How far a temperature departs from normal: the difference from the long-term average.' body: |- A temperature anomaly is how much warmer or colder it is than the local normal for the time of year. Thermograph expresses the same idea as a percentile and a grade (from “Below Normal” to “Near Record”), so an anomaly is easy to read at a glance for any location. - slug: feels-like term: Feels-like temperature short: What the air actually feels like once humidity and wind are accounted for. body: |- Feels-like (apparent temperature) combines air temperature with humidity and wind. In heat it uses the heat index; in cold it uses wind chill. Thermograph grades feels-like against its own local history, so “Near Record” means extreme for that place. - slug: heat-index term: Heat index short: How hot it feels when humidity is factored into the air temperature. body: |- The heat index is the apparent temperature on a hot, humid day: high humidity slows sweat evaporation, so it feels hotter than the thermometer reads. Thermograph folds it into the feels-like metric and grades how unusual it is locally. - slug: wind-chill term: Wind chill short: How cold it feels when wind is factored into the air temperature. body: |- Wind chill is the apparent temperature on a cold, windy day: wind strips away body heat, so it feels colder than the air temperature. It's the cold-weather half of feels-like. - slug: humidity term: Absolute humidity short: The actual mass of water vapor in the air, in grams per cubic meter. body: |- Thermograph reports absolute humidity (g/m³), the real amount of water vapor in the air, rather than relative humidity, which shifts with temperature. Graded against local history, it shows genuinely muggy or unusually dry days. - slug: reanalysis term: Reanalysis (ERA5) short: A gridded, physically-consistent record of past weather for anywhere on Earth. body: |- A reanalysis blends historical observations with a weather model to produce a consistent record of past conditions everywhere, even where no station exists. Thermograph's ~45-year history comes from ECMWF's ERA5 reanalysis (via Open-Meteo), which is why it works for any point on Earth.