This line chart visualizes solar radiation against elevation for global mountain climate data. The blue line and circular markers show the relationship between two continuous variables, sorted by elevation to create a smooth monotone curve using `d3.curveMonotoneX`. The chart uses D3 v7 with `d3.csv` loading, `d3.scaleLinear` for both axes, and `d3.axisBottom`/`d3.axisLeft` for labeled axes with gridlines. Hover tooltips appear through SVG `<title>` elements, displaying each mountain's name, elevation, and radiation value. The data comes from a remote CSV file containing Global Mountain Climate measurements.