Rünkpilvi

Rünkpilvi is an Estonian term referring to a cumulonimbus cloud. These are dense, towering vertical clouds associated with thunderstorms and atmospheric instability. Cumulonimbus clouds form when warm, moist air rises rapidly through the atmosphere. As the air ascends, it cools and condenses, forming water droplets and ice crystals that make up the cloud.

The characteristic appearance of a rünkpilvi is a cauliflower-like shape at its base, while its top can spread out into a flat, anvil-like shape, known as an incus. This anvil forms when the rising air current reaches the tropopause, the boundary between the troposphere and the stratosphere, and can no longer ascend vertically, forcing the cloud to spread horizontally.

Rünkpilvi are responsible for a variety of intense weather phenomena. These include heavy rainfall, hail, lightning, and thunder. In some cases, they can also produce strong winds and tornadoes. The development of rünkpilvi is a key indicator of unstable atmospheric conditions, often seen during warm, humid summer afternoons. Meteorologists closely monitor these clouds as they can pose significant hazards to aviation and ground activities. The presence of rünkpilvi signifies a potent convective system capable of generating severe weather.