By: Laura Ruiz
Classification of clouds
Clouds are classified into cumuliformes (cumulus) and stratiform (strata). Cumuliform clouds originate in strong upward air currents. The surface of its base is flat and the top takes the characteristic shape that makes it similar to the cotton bud. Stratiform clouds or strata are formed when the upward air current is very weak. They extend evenly across the sky, without taking a definite shape.
Types of clouds according to their shape
If we know the shape of the cloud masses their size and the atmospheric layer where they are located, we can have an idea of the type of precipitation to be produced, as well as their intensity.
Nimbostratos: They have the appearance of a regular layer of dark gray color with diverse degrees of opacity. It is sometimes possible to observe a slightly fluted appearance corresponding to varying degrees of opacity and variations of gray color. They are typical clouds of rain of spring and summer and of snow during the winter.
Stratocumulus: They present wide ripples similar to elongated cylinders, being able to present like banks of great extension. These clouds have zones with different intensities of gray. Stratocumulus rarely supplies rain, except when it becomes Nimbostratus.
Strata: They have the appearance of a bank of gray haze without a definite or regular structure can be observed. They show spots of different degree of opacity and variations of the gray coloration. During autumn and winter the Strata can stay in the sky all day giving a sad look to the sky. During spring and early summer they appear during the early morning scattering during the day, indicating good weather.
ALTOCUMULUS Abbreviation: AC. Description: Cloudy mantle of great horizontal extension, composed of individualized clouds of little vertical development, that can cover the sky in its totality, although holes are observed where it will be seen the sky or the Sun or the Moon. The clouds that form this layer are usually gray, but sometimes alternate with a whitish color and are separated from each other, but arranged regularly, as a “brick wall." Most of the small elements that form Altocumulus have an apparent width between 1 and 5º. They receive the popular name of “borreguitos". They can produce irisations and especially “solar or lunar crown", fact that helps us to differentiate it from the stratocumulus. Formation height: Its base is usually about 3,000 meters high, but can range between 2,000 and 6,000 meters. Constitution: They are constituted by water droplets, although at very low temperatures can have in their sine ice crystals. Meteorological situation: They do not produce precipitations, but they usually indicate a clear change of the time, indicating the arrival of a disturbance, if they are increasing or appear along with altoestratus.
ALTOSTRATUS Abbreviation: AS Description: Uniform mantle, of great horizontal extension and certain vertical development; Of grayish or bluish color, of fibrous aspect, can cover the whole sky and sometimes presents parts thin enough to let the Sun or Moon, at least vaguely, as through a dull glass. It does not give halo phenomena, which differentiates it from a cirrostratus. The characteristic of the As is the uniformity of its lower surface giving the sensation of an immense sheet or cover extended from horizon to horizon. Rarely presents holes, although always offers differences of thickness; When it does not completely cover the sky, it usually ends up on one side in a cleanly trimmed rectilinear edge, below which some small clouds, almost always cumulus, can be found. Formation height: Its base is between 3 and 4 kilometers in height, reaching up to 7,000 m. Its thickness can be, including, several kilometers. Constitution: Because they have a certain vertical development, they are constituted by several zones, the low part is formed by water droplets, the middle zone will also have drops of water, but already accompanied by crystals of ice and snowflakes; While the highest part is composed of ice crystals. Meteorological situation: They produce precipitations, in the form of water or snow, normally continuous, but not very intense.
NIMBOSTRATUS Abbreviation: NS Description: Clouds are “rampant" par excellence, being a continuous layer of great horizontal development and moderate vertical growth, dark gray with veiled appearance, can occupy the whole sky and completely hide the sun. It usually covers the entire sky, to which they give a sad and somber appearance; They lack contours and reliefs, or rain or rain is imminent, and in both cases the lower surface of the cloud is so poorly defined that it can be said to be non-existent. This type of cloud is linked to the altostraus, differing from them in that they are thicker and because their base usually descends, which gives a more threatening aspect. It is the thickest of stratified clouds, actually extending from the base of the low clouds to the top of the socks. In addition, when they cover the sky completely, no other sort of average cloud can exist simultaneously, whereas they almost always coexist with some low clouds. Formation height: The formation of its base occurs at very different heights, so it can be considered both a low cloud and a medium cloud. Its thickness is greater than in the case of the altostratus and can reach 4 kilometers. The process of nimbostratus formation is due to the descent and thickening of a higher cloud veil, usually an altostratus, although sometimes it has not been possible to observe this phenomenon behind a somewhat lower cloud layer, for example stratus. Constitution: They are constituted by droplets and raindrops and according to the time of the year and their vertical development, they can also have ice crystals.
Cirrus (Ci): Separate clouds in the form of white and delicate filaments, or of banks, or of narrow strips, white of the whole or for the most part. These clouds have a delicate, silky or fibrous and shiny appearance. Cirrus in the upper part of the atmosphere reveals the presence of moisture and may indicate the arrival of a stormy or warm front. Max height: 10 -11 Km.
Circumulus (Cc): Bench, mantle or thin layer of white clouds, without its own shadows, composed of very small elements in the form of globules, waves, etc., united or not, and arranged more or less regularly; Most of the elements have an apparent diameter of less than one degree. They are signs of jet streams and turbulence. These clouds indicate atmospheric instability and may indicate a storm approach. Max Height: 9 -10Km.
Cirrostratus (Cs): Transparent, thin and whitish cloudy veil, with a fibrous appearance (like hair) or smooth, covering all or part of the sky, letting sunlight and moonlight through. They do not precipitate and usually produce phenomena of halo (solar or lunar). However, its presence usually indicates the arrival of a stormy or warm front. Max height: 9-11 Km.
Altoestrats (As): Greyish or bluish mantle or cloudy, striated, fibrous or uniform appearance, covering all or part of the sky and having parts thin enough to let the sun see, at least vaguely, as through a glass Dingy It is composed of supercooled droplets and ice crystals; They do not form halos, and sometimes these clouds produce snowfall or drizzle, although they are usually at such an altitude that their precipitation evaporates before reaching the ground. Max height: 8-9 Km.
Altocumulus (Ac): Bench, or mantle or layer of clouds white or gray, or at the same time white and gray, that usually have shades of their own, in cottony form, composed of tiles, pebbles, rollers, Times, partially fibrous or diffuse, agglomerated or not. They form the popular “paved sky". Although not necessarily indicative of impending precipitation, these clouds indicate atmospheric instability and possible snow or drizzle. Max height: 7-9 Km.
Vertical development clouds
Cumulus: They present a large size with a massive appearance and very sharp shadows when they are between the Sun and the observer, that is, they are gray clouds. They have a horizontal base and in the upper part large vertical protuberances that continuously deform, presenting an appearance similar to a large cauliflower. Clusters correspond to good weather when there is low ambient humidity and little vertical movement of the air. In the case of high humidity and strong upward currents, Cumulus can acquire a large size resulting in storms and intense downpours.
Cumulonimbos: Large size and massive appearance with a very marked vertical development that gives the impression of mountainous cliffs and whose cusp can have the form of a large mushroom; And has a smooth or slightly fibrous structure where different intensities of gray or cerulean color are observed. These clouds may have large ice crystals on top. The Cumulonimbos are typical clouds of the intense storms being able to produce hail.