This colorful map is pretty simple and easy to understand, thanks to its very clear key. It uses differing color hues to represent differences in temperature. It is not a real data map, however, as it does not describe the actual temperatures across the US at any particular moment in time. The map’s actual purpose seems not to give genuine information about the country, but rather to show off the mapping abilities of the company that made it. We might call it a “demonstration map.” It’s in a portfolio for a company called Brite Research & Consulting, which I assume specializes in mapping data.
The map uses hue, rather than value or saturation, as the distinguishing factor between temperature levels. After using white to signify extremely low temperatures, the map shifts to violet for the second-to-lowest temperature range, and then continues on through the color spectrum to red to signify increasing temperature. The use of hues, as Monmonier notes, can create confusion sometimes, because for most people there is no logical ordering of hues (167-68). However, this map avoids the problem because of its handy key. The use of red is also useful to indicate hot temperatures, while the map’s use of white for the lowest temperatures (rather than violet, the other end of the spectrum from red) draws upon an association with cold snow. The use of these varied hues allows for a neat-looking, visually impressive map. A map of many colors is more interesting than a map of few colors.
To me it also signifies technological advancement, because of its association with the futuristic “thermal vision” goggles seen in movies and video games.