Webcast

Comma Clouds - Mesoscale Features in cold Air

Commas are meso-scale structures developing within cold air, often behind frontal cloud bands. They occur mainly during the cold season and are a common feature for Northern and Western Europe – nevertheless commas can also be found in the south. As commas can cause severe weather this conceptual model is of high interest for forecasters. In this lecture life cycles of commas will be demonstrated and how they appear in satellite imagery – seen by MSG and polar orbiting satellites. On the theoretical side the physics behind these developments will be explained. Different types of development exist - Within the cold air commas can grow out of EC starting as a small feature which is growing in to the typical meso-scale cloud spiral. On the other hand commas can be found in connection with occlusion when they split off the cloud spiral and becoming a separated feature on their own. The most important numerical parameters in connection with commas and their synoptic surrounding will be discussed. Typical weather events are storms and heavy precipitation (in form of showers and thunderstorms). Examples of real cases will be shown and shall illustrate life cycle and typical synoptic situations.

 Lecture slides...

Filed under Keywords:

conceptual models, comma clouds, life cycle