WRAL WeatherCenter Blog

How can you tell the difference between thunderstorm clouds and non thunderstorm clouds?

Posted July 22, 2007 9:02 a.m. EDT

MIKE MOSS SAYS:     Wayne,     Thunderstorm clouds usually become quite tall, often reaching a level called the tropopause that causes the top of the storm to flatten out into an "anvil" shape. Of course, visually and audibly, if a cloud is producing lightning and thunder, it is a thunderstorm. Using radar, we can often identify thunderstorms by how strong the radar reflectivity is and how it is distributed, as this gives us an estimate of rainfall intensity and the possible presence of hail. This is not a perfect method of detection of course. On satellite, thunderstorms can often be seen to extend higher than surrounding cloud cover on visible satellite images and to "colder" levels on infrared imagery. As for forecasting, thunderstorms are usually indicated by certain thresholds of instability (the difference in expected temperature and moisture characteristics near the surface and higher up in the atmosphere) and/or the presence of features that are likely to produce very strong upward vertical motion.