Barometer Simultaneous barometric readings from across a network of weather stations allow maps of air pressure to be produced, which were the first form of the modern weather map when created in the 19th century. Isobars, lines of equal pressure, when drawn on such a map, give a contour map showing areas of high and low pressure. Localized high atmospheric pressure acts as a barrier to approaching weather systems, diverting their course. Atmospheric lift caused by low-level wind convergence into the surface brings clouds and sometimes precipitation. The larger the change in pressure, especially if more than 3.5 hPa (0.1 inHg),
Transit map purpose of a transit map is to help passengers—especially those unfamiliar with the system—to take the correct routes to travel between two points; this may include having to change vehicle or mode in the course of the trip. The map uses symbols to illustrate the lines, stations and transfer points, as well as a system of geographic identification. At the same time the map must remain simple to allow overview, and be usable by those unfamiliar with the geography of the area. Stations are marked with symbols that break the line, along with their names, so they may be referred