Thunderstorm with lightning(Omer Mopen / Unsplash)Weather maps can be confusing with so many different symbols. What do they mean? Learn about a few of them with the latest Science Behind the Forecast.This transcript was edited for clarity and brevity.Bill Burton: It's time for us to take a look at the Science Behind the Forecast as I'm joined by WAVE 3 meteorologist Tawana Andrew. Good morning, Tawana.Tawana Andrew: Good morning. Today we're answering some questions.BB: Last time we talked, we were talking about fronts. There's a lot of other stuff on weather maps, too. So we're picking up where we left off. What are we talking about today, specifically?TA: Specifically, we're going into troughs, squall lines and dry lines. Last time we talked about the cold front, the warm front, the stationary and occluded fronts. Those are the typical ones that you see on a weather map.But the trough is a little bit more interesting when that one pops up, because it's not a stereotypical weather boundary. It's more of an elongated area of lower atmospheric pressure and unstable air. Think of an area of low pressure that just got stretched out a little bit too much, and these are denoted on a weather map by black or brown lines. They don't have semi circles or triangles on them. They just kind of sit there.BB: They're flat and elongated, just like a trough.TA: Exactly. While there are no changes within the air mass itself, as you travel along a trough, your wind direction will shift, so you'll see that kind of a change as it moves through. Troughs are more indicative of changes in the upper levels of the atmosphere, not as much towards the surface. However, they can still trigger showers and thunderstorms as they pass by.Then switching gears to a squall line. A squall line is a line of thunderstorms that can form along or ahead of a front. What happens with a squall line is that you have this rain-cooled air surging out ahead of it, and that can actually trigger additional thunderstorms to form along that outflowing wind and that outflow can kind of act as a cold front on its own. That pushes storms a little bit faster well in advance of a front. We typically see squall lines a lot at this time of the year. This is something that you'll typically see popping up a little bit more in the spring on weather maps. They are denoted by a line of dashes separated by two dots.BB: Dots and dashes. Morse code comes to the weather forecast?TA: Basically. You can't really interpret it in terms of Morse code, but you can definitely interpret it in terms of severe weather.BB: It’s not spelling something, you're just letting people know what's coming.TA: Exactly. With the squall line, you'll get that arch line of thunderstorms, typically known as a bow echo. These can produce anything from strong straight line winds to tornadoes. They're interesting to see on the map, but we usually don't get excited when we see squall lines showing up.Then the last one for today is a dry line. This indicates the boundary between dry air and very humid air in an area. That dry line basically forces that saturated air up into the atmosphere as it pushes to the east. Since dry air is less dense than humid air, that can produce severe and even tornadic thunderstorms. These boundaries are usually oriented from north to south, and they're seen at this time of the year a lot, but not so much in Kentucky and Indiana. This is more of a plains issue. So towards Texas, Oklahoma, Kansas. ...read more read less