Gray early morning sky shows signs of clearing.A cold front has passed in the past 4 to 7 hours.Wind shifts to West, especially from East through South.Light, scattered clouds alone in a clear sky.Impending Strong Winds Weather Indicators: Wind (especially North wind) shifting to West and then South.Increasing South wind with clouds moving from the West.Transparent veil-like cirrus clouds thicken, ceiling lowers.Sounds are very clear and can be heard for great distances.Distant objects seem to stand above the horizon.Impending Precipitation Weather Indicators: Temperature far above or below normal for the time of year.Strong wind and/or a red sky in the morning.If on land, leaves that grow according to prevailing winds turn over and show their backs.Wind shifting North to East and possibly through East to South.Clouds moving from East or Northeast towards the South.Clouds at different heights moving in different directions.Clouds increasing in numbers, moving rapidly across the sky.Sky is dark and threatening to the West.Puffy clouds begin to develop vertically and darken.Clouds lowering and thickening, ceiling lowers.

Cirrus castellanus - More vertically developed than cirrus floccus, cirrus castellanus have turret-like tops and are taller than they are wide.

These have a more cotton wool-like appearance than the rest of the cirrus family

Cirrus floccus - Ragged cirrus patches which are much larger than cirrocumulus floccus.

A thick, dense cirrus layer that dominates much of the sky above, often formed by passing warm fronts or the remnants of a cumulonimbus incus

Cirrus spissatus - These clouds sit right at the top of the troposphere.

These wispy streaks of cirrus cannot be seen without a characteristic 'flick' at the end of its tail

Cirrus uncinus - With its trademark hook shape, cirrus uncinus is famous for looking like a horse's tail.

These are the most common type of cirrus cloud

Cirrus fibratus - Thin and fibrous, cirrus fibratus are often aligned with the high altitude wind direction, making for white parallel stripes which streak across the sky.

How do we categorise cirrus clouds?Ĭirrus clouds have five defined 'species' Technically these clouds produce precipitation but it never reaches the ground. Instead, it re-evaporates, creating virga clouds.

They often form in advance of a warm front, where the air masses meet at high levels, indicating a change in the weather is on the way. What weather is associated with cirrus clouds? These streaks can spread out and become cirrus, cirrostratus and cirrocumulus. Cirrus is made up completely of ice crystals, which provides their white colour and form in a wide range of shapes and sizes.Ĭirrus clouds can also form through contrails, the vapour trails left by planes as they fly through a dry upper troposphere. How do cirrus clouds form?Ĭirrus clouds form from the ascent of dry air, making the small quantity of water vapour in the air undergo deposition into ice (to change from a gas directly into a solid). While the Sun is setting or rising, they may take on the colours of the sunset. In the daytime, they are whiter than any other cloud in the sky. These delicate clouds are wispy, with a silky sheen, or look like tufts of hair. Cirrus clouds are short, detached, hair-like clouds found at high altitudes.

Mountain weather indicator clouds clear