Altostratus Undulatus

Above: Altostratus Undulatus

Altostratus Undulatus

Altostratus undulatus clouds can be defined as a form of altocumulus clouds. As the name would suggest, these sorts of clouds normally have undulations at their base. These undulations can be visible as wave-like patterns at the base of the clouds, but most of the time they are invisible to the naked eye.

What height are altostratus undulatus clouds found?

Altostratus undulatus clouds normally form at an altitude of between 6,500 and 16,500 feet (2,000 to 5,000 meters above sea level)

Classification of altostratus undulatus clouds

In cloud classification nomenclature, altostratus undulatus is classified in the medium-level genus. This is due to the fact that these clouds occur at an altitude that can be considered as average for most cloud types.

How are altostratus undulatus clouds formed?

As with most other types of clouds, altostratus undulatus clouds from when condensation occurs. However, a hallmark of formation that determines whether the cloud will be altostratus undulatus is the circumstances surrounding the formation. For this particular type of cloud, a large air mass has to be lifted, leading to condensation at the altitude of this cloud. This has to be combined with elements of wind shear, which shapes the clouds.

The signature appearance of the altostratus undulatus clouds can be attributed to the wind shear. Wind shear occurs when a layer of air slides over another layer. These two layers of air are usually moving at different speeds or towards different directions when they meet. The eddies created at the interface of these layers of air are responsible for cloud formation and also sculpturing of the said cloud to give it that undulating base that gives the clouds their name.

What do altostratus undulatus clouds look like?

Altostratus undulatus clouds have a wavy appearance due to the way that they are formed. These waves are normally parallel to each other, but there are scenarios where the waves cross link as well. The exact morphology of each cloud is affected by:

  • Degree of wind shear
  • How much moisture is in the air mass
  • Physical attributes of wind shear such as speed, intensity etc


Depending on the above variables, the altostratus undulatus clouds may have a morphology ranging from mild furrowing to formation of waves that aren’t connected by any cloud.

How common are altostratus undulatus clouds?

Altostratus undulatus clouds can be seen in any part of the world. However, they are most common in zones with inversion surfaces, where wind shear is likely to occur.

Where can I see altostratus undulatus clouds?

These clouds can be seen in any part of the world, as long as the variables that are needed to form them are present. However, there are certain areas in which one may have a greater chance of seeing these clouds. A good example of such an area is the Southern Plains in the US. To see these clouds in this area, one has to be there during such a time as the initial stages of destabilizing return flows.  

Back to Top