Today we're talking about fronts in aviation. To put it simply, a front is a boundary layer between two types of air masses. Now, for pilots, you need to be paying attention because any approaching front means that there is going to be a change in the weather. There are four types of we have warm fronts, cold fronts, stationary fronts, and also occluded fronts. Each type of front brings its own general weather conditions. However, no two fronts are going to be exactly the same. A warm front is going to occur when we have a warm air mass advancing and replacing a cold body of air, covering the colder air from the top and forcing the cold air out below. This type of front moves rather slowly, typically around 10 to 15 miles per hour. Now, generally, warm fronts have high humidity, and because the air is forced upward by the frontal change, you'll see stratiform and ciri type of clouds and also some fog can be expected along the way. In summer months, this lifting action can trigger cumulonimbus clouds. Now, in this case, precipitation will be light to moderate and then is going to be accompanied by poor visibility during the passage of the front. Stratiform clouds are also visible. You may see some drizzle and then also the visibility is going to be poor, but is going to improve. If we have variable winds after the passage of the front, the visibility eventually is going to improve, but hazy condition may also exist for a short period of time. After the passage, there's generally a slight rise in barometric pressure as well, followed by a decrease of that barometric pressure as the front goes by. Now let's talk about cold fronts. Cold fronts are pretty much the opposite of warm fronts, with the colder air at the surface forcing the air up and away as the front is going to move. Cold fronts generally move at 25-30 mph, but some cold fronts have actually been recorded up to 60 miles per hour. In extreme cases, this quick movement of warmer air upwards is causing the creation of clouds. Now, depending on the stability of the warmer air mass, the cloud types is going to change. Typically, these clouds are going to be either towering cumulus or cirrus type clouds. However, we may see some cumulonimbus as well. Now, depending on the intensity of the cold front, cumulonimbus clouds can also result in lightning, thunder, hail, hail and even some tornadoes. In some cases, after the frontal passage, towering cumulus clouds will begin to dissipate and the precipitation are also going to decrease. In some cases, where a fast moving cold front is present, we will see squall lines, squall lines are narrow bands of thunderstorms that form ahead of the cold front. They're very intense and can move very quickly. Make sure that you avoid squall lines when you're flying. Now, let's do a quick comparison of warm versus cold fronts. Warm fronts generally bring low ceilings, poor visibility, and some rain. Warm fronts occur more slowly, provide warning of the incoming front, and are generally less intense than cold fronts. Now, cold fronts, on the other hand, approach with very little warning and can completely change the weather in a few hours. Weather clears rapidly after a cold front, and the weather that did occur is going to be more intense. All right, let's move on to stationary fronts. Stationary fronts are going to occur when the forces of two air masses are mostly equal. A stationary front can sit over an area for a prolonged amount of time, and those weather conditions associated with a stationary front are generally going to be a mix of the cold and the warm front conditions. Now, finally, let's take a look at occluded fronts. Occluded fronts occur when we have a faster moving cold front that catches up to a slower moving warm front. To make things complicated, we actually have two different types of variants of occluded fronts. We have a cold front occlusion and we have a warm front occlusion. During a cold front occlusion, what we see is we have the cold front air mass that is colder than the warm front air mass. Now, the cold air mass is going to replace the warmer air and then create a mixture of weather that we find in both of these frontal passages. A warm occlusion is going to occur when we have the warm front's cold air mass that is colder than the cold fronts air mass. When this occurs, the cold front is going to ride up and travel over the warm front cold air mass. Generally, a warm occlusion weather is going to be more severe than the cold occlusion with embedded thunderstorms, rain, and fog. Now that you know everything about fronts, check out this video where we talk about high and low pressure systems. Thanks for watching. We'll see you in the next one.