A pie chart visualizes the distribution of temperature readings from a weather CSV file across three ranges: low, medium, and high. It shows the proportional count of cities in each category using colored slices with labels. The visualization is built with D3 v7, fetching and parsing the external CSV via `d3.csvParse`, then using `d3.pie`, `d3.arc`, and an ordinal color scale to construct the SVG arcs. A separate HTML legend is generated from the same data, with color swatches and category labels.