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Fractus cloud

earth science Maturity 5-7 Next article →

Fractus clouds are small, irregular cloud fragments that appear ragged and shredded. They are often described as looking like torn pieces of cotton candy. These clouds are classified as accessory clouds. This means they are not independent structures. Instead, they are formed when pieces break off from a larger, ambient cloud. They usually exist beneath the base of a parent cloud. Because they lack clearly defined bases, they often seem to change shape rapidly.

Cloud against dark blue sky
Cloud against dark blue sky

The formation of fractus clouds is driven by wind and air movement. Strong winds often shear these fragments away from a main cloud. This shearing action creates their characteristic jagged and shredded appearance. These clouds are highly dynamic and can form or dissipate very quickly. Sometimes, they develop because the ground heats up. This heat triggers convection, which is the process of rising air. If convection is strong enough, these small fragments may eventually develop into full cumulus clouds.

There are two principal forms of these accessory clouds. The first is cumulus fractus, which was formerly called fractocumulus. These clouds look like ragged versions of standard cumulus clouds. They can also appear as white, ragged fragments that are spaced far apart. These fragments may originate from cumulus clouds that have already dissipated. The second principal form is stratus fractus, formerly known as fractostratus. You can tell stratus fractus apart from cumulus fractus by several features. They have a smaller vertical extent and a darker color. Additionally, their particles are more widely dispersed.

Scientists use specific names for different groups of these clouds. When multiple masses of fractus clouds gather under a main cloud, they are called pannus or scud clouds. Another specific type is fractonimbus. These are dark-gray, ragged clouds that form under clouds that are producing precipitation. Examples of such parent clouds include nimbostratus, altostratus, or cumulonimbus. While fractonimbus exist under rain-producing clouds, they do not produce precipitation themselves. Over time, they may merge completely with the nimbostratus clouds above them.

Ns1
Ns1

Other specialized forms exist in specific environments. Stratus silvagenitus clouds are a type of scattered stratus fractus. These often appear as ragged tufts of cloud that seem to rise directly from forests. This usually happens just after rain or during periods of high humidity. Observing these clouds provides important data about the atmosphere. Specifically, fractus clouds give an indication of wind movements occurring under a parent cloud. They act as a visual map of how air is moving in that specific layer.

In the context of thunderstorms, scud clouds play a significant role. During rainstorms, scud often forms in the updraft area. This occurs because precipitation from a downdraft cools the air. This cooling causes condensation to happen below the main cloud deck. Scud clouds are very common on the leading edge of a thunderstorm. They often appear when warm, moist air is lifted by a gust front. In these situations, scud is frequently found underneath shelf clouds.

Scud clouds before thunderstorm
Scud clouds before thunderstorm

Monitoring the movement of scud can tell us about the strength of a storm. If the scud is rising and moving toward the main updraft, the thunderstorm may still be developing. This development is sometimes marked by a wall cloud or a rain-free base. Scud can form in both inflow and outflow areas of a storm system. By studying these small, ragged fragments, meteorologists can better understand the complex life cycles of larger storm systems and the turbulent air movements that drive them.

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File:Cloud against dark blue sky.jpg
Cloud against dark blue sky.jpg
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Ns1.jpg
File:Scud clouds before thunderstorm.jpg
Scud clouds before thunderstorm.jpg
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