Cirrostratus clouds

Cirrostratus cloud are thin, layered, can cover the entire sky and formed from ice crystals.

Characteristics.

Cirrostratus are transparent high clouds which can produce a halo effect. The halo is made from white or coloured rings, spots or arcs of light circling the Sun or Moon and can be the only indication that Cirrostratus clouds are in the sky. Cirrostratus cover large areas of the sky, spaning thousands of miles.

Cirrostratus are either filimented, smooth or fibrous and are often seen fringed with cirrus clouds. Cirrostratus clouds are thin enough that shadows can still be cast by the Sun unlike altostratus clouds which are just too thick to allow the sun to cast a shadow.

What's in a name?

cirrus - lock or tuft of hair. Stratus - to spread out, extend, flatten, layer.

How was it made?

Cirrostratus clouds can form as a result of slowly rising air. Generated at the leading edge of frontal weather systems, cirrostratus movements of are a good predictor of what the weather will do in the next day.

Cirrostratus clouds also form from the vapour trails, contrails as aircraft fly through the dry upper troposphere. The contrails spread out and become cirrus, cirrostratus and cirrocumulus clouds.

What weather will you have if these are overhead?

Cirrostratus donot produce rain or snow. If cirrostratus nebulosus is seen an incoming warm front could bring persistent rain within a day. Cirrostratus fibratus on the other hand will be followed by stratus meaning only light drizzle.

How high is it?

Anywhere from 7,000m (20,000ft) up to 13,000m (40,000 ft).

The outcome for you.

Dry and some sun but may be wet tomorrow.