Cloud Formations

Photographs of common, and some less common, Cloud Formations

 

High-level Clouds above 6,000 metres

Cirrus Clouds

Cirrus clouds are high level clouds at an altitude in excess of 6,000 metres (20,000ft). At this altitude the condensing water vapour usually forms tiny ice crystals. These clouds often look like "wisps or curls of hair, hence their name "Cirrus". They are usually a phenomena of good weather appearing only in a stable atmosphere.

At dawn and dusk light from the sun reflecting upon these cloud formations often produces spectacular and colourful displays. Similarly refracted light from the sun, or even the moon, may cause other interesting optical effects such as "coronas".

CIRRUS CLOUDS

Individual and Scattered

High level individual scattered Cirrus cloud formation

 

High level individual scattered Cirrus cloud formation

 

CIRROSTRATUS CLOUDS

Status or Layered

High level layered Cirrostratus cloud formation

 

High level layered Cirrostratus cloud formation

 

Mid-level Clouds between 2,000 and 6,000 metres

Alto Clouds

These are mid level, between 2,000 and 6,000 metres (6,500 and 20,000ft), cloud formations where the condensing water vapour usually remains as water droplets but ice crystals can form when the temperature is low enough.

ALTOCUMULUS CLOUDS

Individual and Scattered

Mid-level individual scattered Altocumulus cloud formation

 

Mid-level individual scattered Altocumulus cloud formation

 

ALTOSTRATUS CLOUDS CLOUDS

Status or Layered

Mid-level layered Altostratus cloud formation

 

Mid-level layered Altostratus cloud formation

 

Low-level Clouds below 2,000 metres

Cumulus Clouds

With their base below 2,000 metres (6,500ft) these clouds are usually composed of water droplets but once again when temperatures are low enough they made contain particles of ice and/or snow. Formation of Cumulus clouds is associated with an unstable atmosphere. Scattered formations of Cumulus clouds are often called "shower clouds" whereas formations of Cumulostratus are often provide "rain clouds" and are prevalent when the sky is "overcast" or completely obscured by cloud.

CUMULUS CLOUDS

Individual and Scattered

Mid-level individual scattered Cumulus cloud formation

 

Mid-level individual scattered Cumulus cloud formation

 

CUMULOSTRATUS CLOUDS

Status or Layered

Mid-level layered Cumulotratus cloud formation

 

Mid-level layered Cumulotratus cloud formation

 

Vertical Formations

Cumulo-Nimbus

Vertical cloud column

Towering vertical Cumulo-Nimbus cloud formation

 

Towering vertical Cumulo-Nimbus cloud formation

 

Cumulo-Nimbus

These vertical cloud formations, illustrated on the right, are usually associated with thunder storms and storm cells.

 

Unusual Cloud Formations

Lenticular Cloud Formation

Lenticular Cloud Formation

 

Lenticular clouds are formed due to wind current lifting moisture laden air over mountain tops. They can also form as a result of air waves moving of hilly or undulating terrain.

 

Banded Cloud Formation

Banded Cloud Formation

 

Banded clouds are formed due to wind currents or pressure waves moving through the atmosphere. They can also form as a result of air waves moving of hilly or undulating terrain.

 

Vapour Trails or Contrails

Vapour Trails or Contrails

 

Vapour Trails or Contrails are created as a result of the water vapour in the exhaust gases of jet engines freezing and forming ice particles at high altitude. The narrow trail is eventually spread out and dispersed by the wind.