1.2.1. Typical thunderstorm – Cumulonimbus capillatus incus
The most distinctive and typical cloud shape associated with thunderstorms is Cumulonimbus capillatus incus: a convective tower (updraft) flattened into an anvil shape. As we have already seen in the previous chapter, it literally looks like an anvil. It is typically over 10 km high and sometimes reaches so high up, it turns day into night for anyone underneath it.
If you see a cloud of this shape from a distance – that is a thunderstorm. While other varieties of cumulonimbus clouds also produce thunderstorms, the anvil shaped incus is the most distinctive – and associated with the strongest thunderstorms.
Why is it this shape? Let us see.