The clouds are formed by the cooling of the air. This causes condensation of water vapor, invisible, in droplets or visible ice particles. The particles are so small that slight vertical currents hold them in the air.

The differences between cloud formations are due, in part, to the different condensation temperatures. When it occurs at temperatures below freezing, the clouds are usually formed by ice crystals; However, those formed in warmer air usually contain water droplets.

The movement of air associated with the development of clouds also affects its formation. The clouds that are created in air at rest tend to appear in layers or strata, while those that are formed between winds or air with strong vertical currents have a great vertical development.

There are several kinds of clouds, which we can classify into three groups: high clouds, medium clouds and low clouds.

High clouds

Cirrus: They are white clouds, transparent and without internal shadows that have an aspect of long and thin filaments. These filaments can have a regular distribution in the form of parallel lines, either straight or sinuous. Occasionally the filaments have a muddled shape. The overall appearance is as if the sky had been covered in brushstrokes. When cirrus clouds invade the sky it can be estimated that in the next 24 hours. there will be a sudden change of time; With temperature drop.

Cirrocumulus: They form an almost continuous layer that presents the appearance of a surface with fine wrinkles and rounded shapes like small cotton flakes. These clouds are totally white and have no shadows. When the sky is covered with Cirrocumulus it is often said that it is abhorred. The Cirrocumulus frequently appear next to the Cirros and usually indicate a change in the weather in the next 12 hours. These types of clouds usually precede storms.

Cirrostratum: They have the appearance of a veil, being difficult to distinguish details of structure, occasionally presenting a long and wide striatum. It edges has definites and regulars limits. These types of clouds usually produce a halo in the sky around the Sun or the Moon. Cirrostratum usually happens to Cirros and preludes the arrival of bad weather due to storms or warm fronts.

Average clouds

Altocumulus: They look like medium sized flakes and irregular structure, with shadows between the flakes. They have undulations or wide stretch marks at the bottom. Altocumulus usually precede the bad weather caused by rains or storms.

High strata: Thin layers of clouds with some dense areas. In most cases it is possible to visualize the Sun through the cloud layer. The appearance of the Altostratus is that of a uniform layer of clouds with irregular spots. Altostratus usually presage fine and persistent rain with temperature drop.

Low clouds

Nimbostratos: They look like a regular dark gray layer with varying degrees of opacity. With a certain frequency it is possible to observe a slightly striated appearance that corresponds to varying degrees of opacity and variations of the gray color. They are typical clouds of spring and summer rain and snow during winter.

Stratocumulus: They have wide undulations similar to elongated cylinders, and can be presented as large banks. These clouds have areas with different intensities of gray. Stratocumulus rarely provide rain, except when they are transformed into Nimbostratos.

Strata: They have the appearance of a gray mist bench without being able to observe a defined or regular structure. They have stains of different degree of opacity and variations of the gray color. During the fall and winter the Strata can remain in the sky throughout the day giving the sky a sad look. During spring and early summer they appear during the morning dispersing during the day, indicating good weather.

Vertical Development Clouds

Clusters: They have a large size with a massive appearance and very marked shadows when they are between the Sun and the observer, that is, they are gray clouds. They have a horizontal base and on the upper part large vertical protrusions that are continuously deformed, presenting an aspect similar to a large cauliflower. The Clusters correspond to good weather when there is low ambient humidity and little vertical air movement. In the case of high humidity and strong updrafts, the Clusters can acquire a large size causing storms and heavy downpours.

Cumulonimbus: Large in size and massive appearance with a very marked vertical development that gives the impression of mountainous cliffs and whose cusp can have the shape of a large mushroom; and that has a smooth or slightly fibrous structure where different intensities of the gray or cerulean color are observed. These clouds can have large ice crystals on top. Cumulonimbus are the typical clouds of intense storms and can produce hail.

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