Cumulus Velum

Above: Cumulus Velum

Cumulus Velum

Cumulus velum clouds are the sail-shaped clouds and they appear as a thin sheet of cloud. It is through this thin sheet of cloud that cumulus clouds grow. The velum clouds are caused by the cumulus which grows through the pileus cap and later turns to be part of the major cumulus clouds. After the cap becomes a portion of the cumulus, the clouds tend to row and become cumulonimbus velum. It is possible to see velum clouds as a horizontal extension that is located above the top of cumulus clouds and sometimes adjacent to the to one or more cumulus clouds.

What height are the cumulus velum clouds found?

They are found in heights of about 6000 meters and are composed of crystals that are formed from the super-cooled droplets of water.  These clouds are largely formed during fair weather and at their elevation; they can point in the direction of the moving air.

Classification of cumulus velum clouds

Depending on the nature these clouds can be classified into the following major cumulus clouds:

  • Cumulonimbus velum – This is realized when a thin layer of clouds merges with cumulus clouds and becomes its part. The cumulus clouds may then grow to become cumulonimbus velum.


  • Cumulus clouds – These are formed by the growth of the sheet of thin layer to become part of the large convection cumulus clouds.

How are cumulus velum clouds formed?

They are formed when warm air rises to meet a mass of cool air. As the warm air rises, the moisture in it condenses due to the surrounding air which is very cool. The temperature of the air reaches the dew point and condensing water starts to separate from the air that is around it, hence forming the cumulus velum clouds. It depends entirely on the difference in temperature between cold and hot air masses in order to have either large or smaller clouds.

What do cumulus velum clouds look like?

The velum appears as a white or grey strip and is usually spotted just above or even around the sides of convection clouds which include cumulus congestus. Even as the velum clouds mix with the cumulus clouds, they tend to spread over such wide areas. When the more powerful convection clouds burst as a result of the stable air layer, the velum clouds are seen loitering at their flanks. The velum clouds are accessory clouds and can be compared to the pileus clouds as their formation is similar although they are of different natures and of the two, the velum clouds are less attractive and tend to be more ponderous.   

How common are the cumulus velum clouds?

Depending on the nature of the weather these clouds are common and can be seen across the globe. They can be seen hanging around or above the cumulus clouds.

Where can I see cumulus velum clouds?

Velum clouds are distributed across the world and such regions that these clouds cannot be spotted include Antarctica. However, the longest period of time that these clouds can be seen is about forty five minutes. They are spotted around or above a group of convection clouds.

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