Due to the spectacular nature of the clouds and the serious phenomena associated with them, the arcus cloud is one of the most coveted creations of storm chasers in our country. Furthermore, its appearance—its dark side, a dark cloud aligned across one or more levels or platforms, usually accompanied by the rapid movement of an electronic device—makes it very striking to the observer. However, the name "arcus" seems to be used too readily and, sometimes, carelessly.
In this article, we'll tell you everything you need to know about the arcus cloud, its characteristics, and what it indicates.
arcus cloud
According to cloud map classification, cumulonimbus arcus is a cumulonimbus-type storm cloud with the distinctive characteristic of having an arc-shaped base. Even cumulus clouds can be associated with this property. However, for practical purposes, when we use the word "arcus," we mean a severe thunderstorm, and the storm cloud that gives it its name is the cumulonimbus. The base should have a clear arc.
When do they usually form?
In radar terms, when can we expect these types of clouds to form? When processed weather radar data shows us a linear storm system, a squall line.
But more than that, squall lines must also be made up of organized, severe storm cells. The most obvious case is the arc-shaped squall line, known in English as bow echo. Therefore, it is understandable that we have to be careful when using the term arcus cloud, although this is not a problem for experienced storm chasers.
Because the term is sometimes used when a curtain of heavy precipitation is observed on the horizon, which may have a certain arc in its perspective, but only represents the transition between the area without precipitation and the area with precipitation. A front associated with heavy rain, with or without thunderstorms.
Sometimes these clouds can organize themselves into a line several kilometers long. The image in the headline of this news story and the photo below, along with the radar images, correspond to the arc observed in the Bay of Malaga in 2004, which can extend along an arc of almost 50 kilometers. As we saw in 2012, arcs can sometimes be embedded within the structure of other clouds, such as stratocumulus.
cumulonimbus clouds
Cumulonimbus clouds are clouds that develop vertically, meaning they form when there is a low (warm) layer of air and a high (cold) layer of air. This and other more complex atmospheric processes bring enormous amounts of moisture to very high atmospheric regions through the formation of large masses of ice in the upper parts of the clouds from water vapor, and hailstones begin to fall, creating downdrafts.
These large turbulent flows create a lot of friction, which generates static electricity. Over time, this process can become very large until it creates a significant difference in electrical potential between different areas of the cloud or from the ground, eventually producing lightning.
Characteristics of the arcus cloud
Arcus clouds are low, horizontal, wedge-shaped clouds that form an arc. They are also called shelf clouds and attach to the base of parent clouds, usually cumulonimbus thunderstorms, but can form from any type of convective cloud.
The upward motion of the cloud is often seen in the main (outer) part of the cloud shelf, while the lower part is often turbulent and wind-torn. Cold air from the sinking storm cloud spreads to the Earth's surface with a leading edge called a gust front. This outflow is cut off under warm air entering the storm's updraft.
As lower, cooler air lifts warmer, more humid air, its water condenses and forms clouds (wind shear) that are often swept up and down by different winds.
People who see platform clouds may mistake them for wall clouds. This could be a mistake, as the approaching platform of clouds appears to form a wall of clouds. Platform clouds typically appear at the front of a storm , while wall clouds usually appear at the rear.
A strong gust front will cause the lower portion of the cloud platform front to zigzag, bordered by rising fragmentation clouds. In severe cases, eddies develop along the edges, and twisting scuds may reach the ground or be accompanied by rising dust. The very low platform clouds that accompany these signs are the best indicator that a potentially severe storm is approaching. An extreme example of this phenomenon, which resembles an almost tornado, is called a gust.
Consequences
The truth is that when this cloud is in the Earth's atmosphere, it can negatively affect life on Earth. Let's see what its consequences are:
- Ray: This cloud releases electrical storms, a phenomenon that we all experience throughout our lives. Although lightning can damage electrical infrastructure, it is unlikely to reach the human body.
- Floods: Flooding or even overflowing of rivers or lakes can occur due to the effects of heavy rains.
- Hail: This solid precipitation can wreak havoc on agriculture, destroying farmland. In addition, the relatively large sizes of hail can cause injury to those directly affected.
- winds and tornadoes: This type of cloud can cause strong winds that can uproot trees. In extreme cases, a tornado can occur, a phenomenon that destroys everything in its path.
Despite these negative effects, it should be noted that humans have become accustomed to living with this phenomenon, and therefore the risk of an accident caused by an arcus cloud is very low . In other areas, such as air transport, this cloud must be taken into account because its effects can cause significant damage to aircraft, such as lightning strikes or turbulence caused by strong gusts of wind.
I hope that with this information you can learn more about the arcus cloud and its characteristics.