This bivariate area chart visualizes daily high and low temperatures in San Francisco over two years, with the shaded region spanning the gap between these values. The data is loaded from a TSV file using `d3.tsv`, with dates parsed via `d3.time.format`. The visualization encodes time on the x-axis using `d3.time.scale` and temperature on the y-axis with `d3.scale.linear`. The area shape is rendered using `d3.svg.area`, while `d3.svg.axis` displays both axes. The chart applies conventional margins and renders as SVG, with the area filled in steelblue.