A cold air mass moves underneath a warm air mass causing the warm air to rise. This brings showers or thunderstorms, followed by cooler weather this event can be identified as-
This event can be identified as a cold front.
The event you are referring to is called an "occluded front." An occluded front occurs when a cold air mass catches up and overtakes a warm air mass. This typically happens in a complex weather system, such as a mid-latitude cyclone.
To identify an occluded front, you can follow these steps:
1. Look for a low-pressure system on a weather map: Occluded fronts often form within the circulation of a low-pressure system, which is represented by a closed isobar (line of constant pressure) contour.
2. Look for a cold front and a warm front converging: An occluded front forms when a cold front catches up with a warm front. On a weather map, a cold front is represented by a solid blue line with blue triangles pointing towards the warm air, while a warm front is represented by a solid red line with red semicircles pointing towards the cold air.
3. Look for a purple line with alternating semicircles and triangles: An occluded front is depicted on weather maps as a purple line with alternating red semicircles and blue triangles. The semicircles and triangles indicate the motion of warm air rising and cool air sinking.
So, by identifying a low-pressure system, a cold front, a warm front, and a purple line with alternating semicircles and triangles on a weather map, you can recognize an occluded front. This weather phenomenon often brings showers or thunderstorms followed by cooler weather due to the mixing of different air masses.