Cumulonimbus is the name for a cloud commonly seen in thunderstorms. The cumulonimbus cloud is a very large and tall cloud that suggests bad weather is on the way. In a cumulonimbus cloud, the temperature is extremely low, low enogh to freeze a human to death quite easily. There is usually strong winds in a cumulonimbus cloud, and these are also dangerous to a human such as a airplane pilot who ejected from the airplane while inside the cumulonimbus cloud.