monipilviä

Monipilviä is a Finnish term that translates to "cumulonimbus clouds" in English. These are large, dense, and vertically developing clouds associated with thunderstorms and atmospheric instability. Their appearance is often described as towering or mountain-like, with a dark, ominous base and a frequently flattened, anvil-shaped top composed of ice crystals.

The formation of cumulonimbus clouds begins with strong updrafts of warm, moist air. As this air rises, it cools, and water vapor condenses to form cloud droplets. Continued rising and condensation lead to the significant vertical development characteristic of these clouds. Within a cumulonimbus cloud, updrafts and downdrafts can be very strong, leading to precipitation, lightning, thunder, and potentially hail or tornadoes.

Cumulonimbus clouds are a key indicator of severe weather. They can extend through a significant portion of the troposphere, sometimes reaching altitudes of over 12 kilometers (about 7.5 miles). The anvil top, known as the cumulonimbus incus, forms when the updraft reaches the stable layer of the stratosphere and spreads out horizontally. These clouds are a common sight during warm, humid weather conditions, particularly in the afternoon.