Interpreting a Weather Map Since there is a lot of information to display but not a lot of room, symbols are used on weather maps to convey information. You have seen some of these symbols already.

On this map, H and L are used to show areas of high and low pressure. The isobars, or lines around them, connect areas of equal pressure. Isobars look a lot like contour lines on topographic maps, but isobars connect areas of equal air pressures instead of elevation.

Notice that around the center of an L, pressure increases as the bars move away from the center. It’s the opposite around an H; pressure decreases farther away from the center.