Some rare and special clouds

Nacreous clouds are rare and very high clouds, known mainly for the coloured irridescent light they reflect after sunset and before sunrise.

Nacreous clouds form in polar regions from very small ice crystals between 68,500 and 100,000ft. 

Noctilucent clouds are extremely rare very high ice clouds seen in the night sky on clear, summer nights. They become visible about the same time as the brightest stars.

Noctilucent clouds are found at 200,000ft and only seen between latitudes 45 and 80 degrees North and South.

Mammatus clouds are some of the most unusual and distinctive cloud formations with a series of bulges or pouches emerging from the base of a cloud.


Mammatus clouds are usually formed in association with large cumulonimbus clouds. They indicate hail, heavy rain and lightning. 

Lenticular clouds form when the air is stable and winds blow across hills and mountains from similar directions at different heights. They have bases between 6,500 and 16,500ft.

Lenticular clouds are believed to be one of the most common explanations for UFO sightings.

When rain falls from a cloud but evaporates before it reaches ground it can create wispy tails from medium and high clouds. This is called Virga.

Virga are known as the 'jellyfish of the skies'.

A funnel cloud is a cone-shaped cloud which extends from the base of a cloud towards the ground without actually reaching the surface. Funnel clouds almost always form from a cumulonimbus. 

If a funnel cloud touches the ground it becomes a tornado. 

These are extremely rare phenomenon, where a cloud produces a billowing wave pattern. They occur when two different layers of air in our atmosphere are moving at different speeds (a phenomenon known as shear). 

These clouds are named after two physicists who studied turbulance.