Abstrakt
The paper focuses on convective storms which exhibit a distinct long-lived cold ring at their cloud top, as observed in enhanced infrared window satellite imagery. The feature seems to be closely linked to a similar phenomenon, cold-U shape, or in general to storms which exhibit an enclosed warm area downwind of the overshooting tops, surrounded by colder parts of the storm anvil.
While storms exhibiting warm spots seem to be quite common, storms exhibiting distinct cold rings or cold-Us are significantly less frequent. The cold-ring feature is described here for storms above the Czech Republic and Austria on 25 June 2006.
This case was extraordinary not only by the magnitude and duration of the cold ring and its central warm spot, but also by cloud-top heights. It also shows that the cloud top height, derived from satellite radiances, has significant error when applied to this type of storm.
We also discuss the potential of the satellite-observed cold-ring feature as an indicator of storm severity.