This D3.js-based visualization gallery presents environmental sensor data from multiple monitoring stations, encoding temperature (x-axis), humidity (y-axis), PM2.5 concentration (point size), station (color), and observation month (animation frame). The example includes three coordinated views: small multiples showing all month subsets side-by-side, an animated playback of monthly data points, and an interactive scatterplot with hover tooltips. Built with D3 version 7, the visualization uses SVG rendering, custom tooltip creation, and programmatic animation to explore seasonal relationships across the five station locations.