As a meteorologist looking at a weather map, whether it be a chart of atmospheric pressure, contours of temperature, or just a jumble of weather symbols, the overall picture is usually crystal-clear to me. Sometimes I take that knowledge for granted, however, and forget that not everyone makes immediate sense of that kind of information. What I consider the basics may look like a foreign language to some, so I thought I would cover some of these basics to help you understand what you might see on your local weather map on any given day. Two letters that are very common on weather maps, are the big blue H and the big red L. The H stands for high pressure and the L stands for low pressure. I joke with school kids that the pressure I'm describing is not the type of feeling they have before a big test they didn't prepare for. I'm talking about air pressure, which is the force of air molecules as they move around, colliding with each other and surrounding objects. On a map of sea level pressure, the H merely marks the center of highest pressure, relative to the levels around it.