While the other cirrocumulus structures are often a bit more challenging to identify, the undulatus is usually more defined and has a finer appearance. In the middle atmosphere of about 3000 to 4500 meters, there exists another cloud type that resembles stratocumulus undulatus in the lower atmosphere.  They are similar in terms of pattern and formation mechanism.  To casually distinguish a stratocumulus undulatus from an altocumulus undulatus, stretch you arm and point your hand towards the cloud strips that are well above the horizon.  If the strip exceeds the width of the middle three fingers, then it is most likely the former. Altocumulus Undulatus are patches or layers of small grains arranged in bands. In addition, while the low clouds have full rounded shapes, the cirrocumulus undulatus can also take the form of billows and rows.

It is the first new formation added to the International Cloud Atlas of the World Meteorological Organization since 1951.

Such clouds are not unique to one geographic area and have been photographed from the United States to Russia. They have a wavy appearance due to wind shear and usually cover only a small portion of the sky. In a nutshell, their overall appearance is of almost perfect horizontal and parallel lines that are leaning according to the direction of the wind.

In fact, the atmosphere is full of waves with different origins.  Some are generated from the boundary between two air layers with different densities and velocities; some are triggered by the upward movement of air forced by mountain range.  These waves induce up and down motion.  When sufficient moisture is present, cloud will form where the wave rises above the condensation level and dissipate where it falls below the level (figure 2).  Eventually cloud strips and gaps are arranged in an alternating pattern.  Stratocumulus undulatus carries limited moisture content and is usually not rain-bearing.  On some occasions, particularly when cloud strips merge together and develop further, it may indicate that rainy weather is on the way. The reason for this is that they are mainly composed out of ice crystals, even though they can seldom include ice or water droplets. Normally, similar to the other cirrocumulus varieties, the undulatus are most common in the cold season, especially in winter. These wave-like structures form on the underside of the cloud to makes it look like a rough sea surface when viewed from below. It is believed that a disruption in the stability of the cloud layer, such as that caused by a passing jet, may induce the domino process of evaporation which creates the hole. This leaves a large, often circular, hole in the cloud. Similar to the cirrus and cirrostratus clouds, the cirrocumulus undulatus structures are considered high clouds. The presence of Altocumulus undulatus may indicate precipitation within the next 20 hours or simply a cloudy day. It is important to note that this type of variety can be found with other main clouds and subcategories such as: In fact, whilst the rounded or elongated shape of the individual clouds that form undulatus may create some difficulties in identifying them, what makes them distinct from other undulatus formations is the clear separation through well defined breaches. In 2009 Gavin Pretor-Pinney, founder of the Cloud Appreciation Society, came across the image and began working through the Royal Meteorological Society to promote the cloud type. Image of high, beautiful, abstract - 75521514 Margaret LeMone, a cloud expert with the National Center for Atmospheric Research has taken photos of asperatus clouds for 30 years, and considers it a likely new cloud type.

Altocumulus Undulatus Asperatus is a rare, newly recognized cloud formation.

Such holes are formed when the water temperature in the clouds is below freezing but the water has not frozen yet due to the lack of ice nucleation particles. It is the first new formation added to the International Cloud Atlas of the World Meteorological Organization since 1951.

In fact, all clouds that have the “cirro” prefix usually require very cold air fronts, generally bellow the freezing point, in order to develop. If the strip exceeds the width of …

When a portion of the water does start to freeze it will set off a domino effect, due to the Bergeron process, causing the water vapor around it to freeze and fall to the earth as well. Unlike the lower cloud undulatus structures, these patterns can be differentiated through their thin appearance.

Altocumulus (From Latin Altus, "high", cumulus, "heaped") is a middle-altitude cloud genus that belongs mainly to the stratocumuliform physical category characterized by globular masses or rolls in layers or patches, the individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus. On the other hand, their constant characteristic is that is that they are always separated by horizontal gaps.

Consequentially, they usually form at around six thousand meters or twenty thousand feet above sea level in the atmosphere. Asperitas (formerly referred to as Undulatus Asperitas) is a distinctive, but relatively rare cloud formation that takes the appearance of rippling waves.

Even though these cloud patterns are not accompanied by rain or snow, according to meteorologists their presence in the western part of the sky usually indicates bad weather for the next day.

Occasionally they form two or more overlapping waveforms. Cirrocumulus Undulatus.

Stratocumulus, being composed of tiny water droplets, can be grayish or whitish.  It belongs to the low cloud group with cloud base height of 2000 meters or below.  It is usually thin with a depth of a few hundred meters and the horizontal coverage often exceeds several kilometers.  Among the varieties of stratocumulus, Stratocumulus Undulatus is most frequently observed and noticeable during autumn and winter.  Quite often, it exhibits itself in the form of regularly arranged rolls or patches, with blue sky in between (figure 1).  This distinctive pattern reflects that the formation of stratocumulus undulatus is closely related to the wavy motion in the air. The fallstreak hole is a large circular gap that usually appears in cirrocumulus or altocumulus clouds.

To casually distinguish a stratocumulus undulatus from an altocumulus undulatus, stretch you arm and point your hand towards the cloud strips that are well above the horizon. It is the first new formation added to the International Cloud Atlas of the World Meteorological Organization since 1951. I discover that there are 10 different types of cloud, 34 subtypes and an infinite number of varieties, but this appears to be an altocumulus undulatus formation.

Photo about Natural blue sky with altocumulus undulatus Clouds formation.

Figure 2.  Schematic diagram showing the formation mechanism of stratocumulus undulatus. Moreover, the outline of these cloud formations is not always very well defined and their edges are not clear all of the times. The simplest way to describe their dramatic shape is with the help of the synonyms and attributes they often get, such as wave clouds, wind row clouds or billow clouds. Wiggins' photograph was posted on the National Geographic website on June 4, 2009. However, their presence also suggests a colder temperature. Moreover, the beauty of this pattern can easily be admired when a few of the formations, driven by winds, overlap each other.

Altocumulus Undulatus Asperatus is a rare, newly recognized cloud formation. However, some people argue that the uniqueness of their shape is simply a result of their high altitude from the ground observer. Following the seasonal march, the northeast monsoon becomes the predominant weather system in Hong Kong during autumn and winter.  Temperatures near the surface drop; moisture contents decrease; and the weather becomes relatively stable with temperature inversion frequently observed in the lower or middle atmosphere.  The most observable change is the quite limited cloud development along the vertical direction.  Cumulus clouds prevailing in the lower atmosphere during summertime would be replaced with stratocumulus in autumn and winter.

The specific form of the undulatus formation is given by the influence of heavy winds. However, it is important to note that what keeps the pattern bundled together is the fact that they are bordered by two different air masses. Their development on the sky is usually considered a sign of good weather, without precipitations. Unlike the lower cloud undulatus structures, these patterns can be differentiated through their thin appearance. They are similar in terms of pattern and formation mechanism.

As the name indicates, the cirrocumulus undulatus are a high altitude cloud formation with an overall rippled shape. Figure 1.  Stratocumulus undulatus observed to the east of the Hong Kong International Airport on 24 November 2003. As the name indicates, the cirrocumulus undulatus are a high altitude cloud formation with an overall rippled shape.

On June 20, 2006 Jane Wiggins took a picture of asperatus clouds from the window of a downtown office building in Cedar Rapids, Iowa. The altostratus undulatus is a type of altostratus cloud with signature undulations within it.

Altocumulus Undulatus Asperatus is a rare, newly recognized cloud formation. These undulations may be visible (usually as "wavy bases"), but frequently they are indiscernible to the naked eye.