What do the blue lines with triangles represent on a weather map and why would the resulting weather be?
The blue lines with triangles on a weather map represent cold fronts. A cold front occurs when a colder air mass is advancing and wedging underneath a warmer air mass, causing the warm air to rise and create precipitation.
As the cold air displaces the warm air, it can lead to the development of thunderstorms, showers, and sometimes severe weather. The weather associated with a cold front can include strong winds, heavy rain, thunderstorms, and a drop in temperature. After the cold front passes, the weather typically becomes cooler, drier, and clearer.