Which type of clouds is associated with severe weather conditions, including lightning and tornadoes?

The type of clouds that are associated with severe weather conditions, including lightning and tornadoes, is cumulonimbus. These towering clouds are characterized by their significant vertical development and can reach high altitudes in the atmosphere.

Cumulonimbus clouds form in unstable atmospheric conditions where warm, moist air rises rapidly, leading to the development of strong updrafts. This process can produce thunderstorms, and within these storms, the conditions may favor the formation of severe weather phenomena such as hail, heavy rain, lightning, and tornadoes. The cloud itself can resemble a cauliflower head due to its large, billowing structure.

In contrast, cumulus clouds are typically associated with fair weather and do not produce severe storms. Cirrus clouds are high, thin clouds made of ice crystals and are not indicative of severe weather. Stratus clouds are low-level clouds that form in layers, typically bringing steady rain or drizzle but not the severe weather associated with cumulonimbus clouds.