To end our review of the different types of clouds We address what is possibly the most striking and interesting cloud, we refer to the cumulonimbus, the second type of vertically developed clouds, although in reality it is the result of a cluster with a greater development.
According to the WMO it is described as a thick and dense cloud, with a considerable vertical development, in the form of mountains or enormous towers. At least part of the summit is usually smooth, fibrous, or striated, and almost always flattened; this part often extends in the form of an anvil or a vast plume. Below the very dark base, appear low torn clouds and precipitation or showers. In addition, these phenomena can be related to Storm clouds indicating unstable atmospheric conditions.
As we said, Cumulonimbus is the next development step, on the ascending scale of convection, to Cumulus Congestus, therefore, they are clouds of great vertical development (the tops are usually between 8 and 14 km high). In our latitudes they originate mainly in spring and summer in unstable situations, which can also be caused by atmospheric pollution which favors its formation.
These clouds are composed of water droplets and ice crystals at the top, or anvil. They also contain large raindrops, snowflakes, ice pellets, hail, and, in cases of extreme instability, hail of considerable size.
They almost always produce storm, that is, precipitation in the form of showers, rain or hail, generally, although also snow in winter, accompanied by gusty winds and electric discharges that occur between clouds or between cloud and ground (lightning).
The Cumulonimbus are the kings of the clouds, the most photographed and the most spectacular. They lend themselves to being photographed in any situation and it is interesting to be able to photograph them in a complete storm sequence. They should not be confused with the Cumulonimbus clouds, since they are taller, and have a fibrous structure at the tops. While it is true that there are many interesting clouds, altocumulus are another variation that deserves mention.
They have two species (Calvus and Capillatus) and no varieties. The cumulonimbus cloud class is notable for its unusual shape and also for the intense thunderstorms it produces. In temperate climates, they are typically found in areas with high humidity and warm temperatures, favoring their formation during the warmer months of the year, although it is not unusual for them to appear in winter. The development of these clouds can also be studied within the context of height and altitude of clouds.
General characteristics of Cumulonimbus
Cumulonimbus clouds are large, dense clouds characterized by the following set of properties:
- Height and vertical development: These clouds can range from low altitudes (less than 2 km) to very high altitudes (up to 20 km in tropical regions). In temperate climates, they typically reach between 10 and 15 km in height.
- Form: Their shape is vertical and bulging, with a flattened top, giving them an anvil-like appearance. This characteristic is due to the strong air currents within them.
- Color: They are bright white in sunlight, but can turn dark and ominous during storms due to the large amount of water and ice crystals they contain.
- Precipitation: They are known for producing intense rain, hail, lightning and strong winds. cold air infiltration at the bottom it can generate significant electrical discharges.
How do Cumulonimbus clouds form?
The formation of Cumulonimbus is related to several key factors:
- Hot and humid air: Warm air warms up upon contact with the ground and begins to rise due to its lower density. This rise is intensified in situations where there are strong convective currents.
- Adiabatic cooling: As the warm air rises, it cools due to the low atmospheric pressure. This cooling causes water vapor to condense, generating the water droplets that form the cloud.
- Atmospheric instability: An unstable atmosphere is required, where temperature differences between warm and cold air masses favor the vertical development of the cloud. Without stability, the cloud cannot grow properly.
- Air currents: The updrafts and downdrafts that occur within the Cumulonimbus are critical to its growth. These currents can reach speeds of up to several hundred meters per minute.
The entire formation process can take from a few minutes to several hours, depending on atmospheric conditions. Once developed, these clouds can persist and change shape over time, displaying different characteristics during their various stages of maturation. This maturation process can be compared to that of other clouds, such as cirrus, which have a different formation and characteristics.
Cumulonimbus species and variants
Within the category of cumulonimbus clouds, there are two main species that have specific characteristics:
- Cumulonimbus calvus: This type of cloud is less developed, with softer tops and less electrical activity. It is an intermediate state before becoming Cumulonimbus capillatus.
- Cumulonimbus capillatus: This is the most mature and developed state, where the characteristic anvil cloud can be observed. These clouds tend to be more intense in terms of precipitation and convective activity.
Cumulonimbus can also generate complementary phenomena, such as clouds mamma, which are protuberances that develop at the base of the cloud, and the arcus clouds, which have a characteristic shape at their base. Sometimes, these visual effects can be as striking as those observed in Pileus clouds.
Impact on meteorology and aviation
Cumulonimbus clouds have a significant impact on the weather and are of particular interest to meteorologists. They can affect air safety for the following reasons:
- Intense turbulence: Rapid changes in pressure and temperature can cause dangerous turbulence that affects aircraft stability.
- Lightning and electric shocks: Cumulonimbus-associated storms are known to generate lightning, which can be damaging to aircraft and their electrical systems.
- Hail: They can produce large hail that poses a serious danger to aviation, damaging fuselages, engines and control systems.
- Low visibility conditions: Heavy rain and dense clouds can significantly reduce visibility, making landing and takeoff difficult.
Therefore, it is essential that pilots and flight crews be aware of the presence of these clouds and stay informed about their development through weather reports and specialized radar systems. Additionally, meteorologists take this phenomenon into account when predicting green storms which are associated with conditions of atmospheric instability.
Cumulonimbus clouds are a fascinating and complex phenomenon that plays a crucial role in our climate. Understanding how these clouds form and develop can help not only meteorologists but also all those who enjoy the beauty and power of nature.
