What Is a Cumulonimbus Cloud?

Cumulus clouds, also called thunderstorm clouds, are a type of cumulus clouds. Cumulus clouds are formed by the adiabatic cooling of air in the form of convective motion, which saturates and condenses water vapor, including light cumulus clouds, dense cumulus clouds, cumulonimbus clouds, and broken cumulus clouds.

The cumulonimbus cloud is thick and huge, and its vertical development is extremely vigorous. From a distance, it looks like a high mountain. The top of the cloud is composed of ice crystals, with white silky-glossy strands, often in the shape of an anvil or horse's bristle. The bottom of the cloud is dark and chaotic, with obvious undulations, and sometimes a suspended spherical structure. Cumulus clouds can be generated inside the air mass or formed on the front. ^[1]

3 necessary conditions to form a cumulonimbus cloud:

1. A lot of unstable energy. To produce convective weather, first the atmospheric layer is unstable. In an atmosphere where a large amount of unstable energy is stored, once sufficient shock force is received, the unstable energy will be released and become the kinetic energy of the rising air movement.

2. Sufficient water vapor. Abundant water vapor is also a necessary condition for the formation of thunderstorms. If there is no sufficient water vapor, even if convection occurs, high thunderstorm clouds cannot be produced. Therefore, thunderstorm clouds mostly appear in times or regions with sufficient water vapor.

3. Sufficient impact force. The presence of unstable energy and water vapor in the atmosphere has the possibility of thunderstorms. In order to make this possible, it is also necessary to have an impact force sufficient to cause the air to rise above the free convection height, so that unstable energy can be released, and the updraft can develop strongly, forming a thunderstorm cloud. ^[2]

Cumulus clouds are divided into two types according to their stage:

(1) Judging by the characteristics of cumulonimbus

Cumulus clouds are more powerful than dense cumulus clouds. The top is white and the edges are not as clear as dense cumulus clouds. The top of a strong cumulonimbus cloud extends from the cloud body to the surroundings. From the side, it looks like an anvil or horsehair for ironing. Shape, very dark at the bottom, rolling ball.

(2) Judging cumulonimbus clouds based on changes in meteorological elements

The cumulonimbus clouds are mostly weather phenomena such as bursts of precipitation, thunderstorms, hail, and crickets. There are occasional tornadoes on the bottom of the cloud, and the cloud base is dark and chaotic. There are often rain storms, suspended spherical clouds, solitary clouds, rolling clouds, and broken Low cloud cumulonimbus clouds vary widely in thickness and are hidden in rain stratum clouds or high-level clouds. The cloud base is similar to rain stratum clouds and high-level clouds. The thickness of the rain stratum is relatively consistent, the sky is uniform in brightness, and there is no significant change in wind and air pressure. When there are cumulonimbus clouds, wind and air pressure will change significantly. When cumulonimbus clouds are observed at dusk, dawn, and at night, when cumulonimbus clouds develop vigorously during the day, there may still be cumulonimbus clouds without attenuation at night, and they may even develop more intensely. If it disappears, it will transform into cumulus stratocumulus or cumulus altocumulus. At night, you can see the cumulonimbus clouds by moonlight and lightning in the clouds.

(3) Judging cumulonimbus clouds and thunderstorms based on various special clouds

Thunderstorms are caused by electrical discharges in the clouds, between clouds, and between clouds and ground. It is the product of the vigorous development of cumulonimbus clouds. There must be cumulonimbus clouds when there are thunderstorms, and thunderstorms do not necessarily occur when there are cumulonimbus clouds. Therefore, when cumulonimbus clouds appear, attention should be paid to the observation of thunderstorms. When there are fortified altocumulus or flocculent altocumulus clouds in the morning, it indicates that the upper air layer is unstable and there is a strong turbulent mixing in the wet air layer. Convective weather occurs when the updraft breaks through the stabilization layer. Therefore, fortified clouds and flocculent clouds are a sign of an afternoon thunderstorm. ^[3]

Cumulus clouds often bring thunderstorms and hail, which are related to the structure of cumulus clouds. Cumulonimbus clouds are usually quite large. A cumulonimbus cloud is a precipitation cell in a torrential rain area. Although the level of each cell is only 1 km to 20 km, they are arranged to form 100 km to 200 A kilometer wide rain belt.

The updraft in the cumulonimbus cloud is very strong, with a vertical speed of 20 m / s to 30 m / s and a maximum of 60 m / s, which is greater than the typhoon wind speed. In such a strong updraft, the water droplets are constantly increasing, and the water content is also significantly increased, reaching more than 10 grams per cubic meter in some areas. If the water vapor supply is sufficient and continuous, then this violent updraft will not be able to support the increasing water droplets, so it will fall and form a torrential rain.

On the other hand, cumulonimbus clouds are constantly expanding, spreading from its top to both sides. Although the pressure on the cloud makes it rise higher and higher, at some point this state will end, and it will no longer have the strength to expand upwards. At this moment, it began to spread out to both sides, countless small water droplets and small ice particles whistling and flying around. Each small particle has a charge-either a positive charge or a negative charge. The cloud became larger and larger, with positively charged water droplets preferring the upper layer of the cloud, while negatively charged ones liked the lower layer of the cloud. The cumulonimbus clouds grow every minute and every second, and the water droplets increase at an extremely fast rate. At the same time, the voltage in the cloud also rises and rises. At a certain time, they must be released outwards, and lightning is thus produced.

Thunderstorms, hail and high winds caused by cumulonimbus clouds often destroy buildings, cause fires, interrupt transmission lines, hinder aircraft flight, and interfere with radios receiving telecommunications. But it also has a "good" side-cumulonimbus clouds contain abundant water resources. If calculated based on an average water content of 2.5 grams per cubic meter of cumulonimbus clouds, a cumulonimbus cloud with a radius of 5 kilometers has a total water content of 1.3 million cubic meters, which is equivalent to the water storage capacity of a small reservoir. If fully utilized, it will greatly help to improve drought. ^[4]