Not all clouds are easy to categorise into a certain type, height or form. Some are very rare and only develop in specific circumstances. Here's a guide to observing other cloud phenomena, including noctilucent night clouds and contrails.
Clouds are commonplace in the sky across most parts of the Earth, and while some occur on an almost daily basis, others are seen much less often. Below is a selection of some other clouds that you may have spotted from time to time and wondered what they were.
For more information on cloud spotting and pictures of different types of clouds, view our cloud types for observers guide.