Today I will be talking about weather fronts and systems, as the vague title might have suggested to some of you ;). Weather fronts are boundaries between two masses of air of different densities. I will discuss the different fronts and pressure systems today. I will also talk about how these are used to forecast the weather.
A cold front is the leading edge of a cool mass of air (I don't mean that the air is super popular, I mean 'brrr'). On a weather map, it is show as a blue line with triangle on the line pointing the direction of travel of the front, as you can see on the left. Cold fronts are made of cold air, so they push up the warm air, causing lowered pressure along the cold front. See the diagram below.
The lowered pressure means that a cold front will generally be accompanied by unpleasant weather, such as thunder storms or just a cooling of the temperature. A cold front moves faster than a warm front. A cold front usually has a high pressure system, so meteorologists can look at a weather map and find the location of a cold front to determine what the weather will be on a given day.
A warm front is the leading edge of a warm mass of air. On a weather map, it is shown as a red line with half-circles pointing in the direction of travel. A warm front is made of warm air, and as it approaches, rainfall steadily increases. It has a lower pressure than cold fronts, so it moves slower than a cold front would. As warm fronts usually have a low pressure system, meteorologists can determine the weather at a given time, same as they would with a cold front.