Except for the general subcategory “Stormy sky”, which contains a wide range of images conveying a dark, turbulent or heavy sky, all others are editorial divisions based on specific storm features. A thunderstorm cloud complex is a three-dimensional process in constant change, but with discernible components that are manifest in the cloud formations. Recognizing these cloud forms will reveal what the storm is doing, providing clues about impending bad weather. Understanding severe storms serves both public safety concerns and educational needs. Many of these images have detailed captions.
The last four subcategories look at the storm environment as a whole, exploring the interrelationship between different clouds or parts of the system. Examples of how storms change, survive and move are in “Evolution” and “Propagation”. “Relationships” looks at cause and effect situations, wherein one event leads to another within the image.