Winds Over the Ozarks

A server route asks Open-Meteo (the same free, open-source weather API behind the living logo) for current wind speed and direction at ~140 points on a half-degree grid covering southwest Missouri and the Arkansas Ozarks — one HTTP call, cached for 30 minutes. The same call returns hourly forecasts, so the time slider above scrubs the next 24 hours of flow without another request. The faint color wash under the particles is the same data, blurred: navy is calm, gold is wind.

The animation technique is borrowed from cambecc/earth (the famous earth.nullschool.net wind globe) and mapbox/webgl-wind: spawn ~1,400 particles at random, move each along the wind vector at its location, draw a short segment per frame, and fade the whole canvas slightly each frame so trails linger. Wind between grid points is bilinearly interpolated on the u/v components — interpolating compass directions directly would glitch at the 359°→0° wrap.

u = −speed × sin(direction)   // direction is where wind comes FROM
v = −speed × cos(direction)
position += (u / cos(lat), v) × dt

The big open-source wind visualizations render the entire planet from global model files. We deliberately didn’t self-host one of those — a 200-line canvas fed by one cached API call does the regional job with zero pipeline to maintain. Knowing when not to deploy the big system is most of the engineering.