Thin clouds, low and thick clouds, cirrus clouds, cirrocumulus clouds, blind altocumulus clouds, what else do you know? What are their characteristics?

Characteristics of clouds

The formation and growth of clouds is a very complex physical process, which is based on the temperature, humidity, air flow, condensation nuclei and the number of ice nuclei in the atmosphere at that time. The interaction of many factors creates colorful cloud shapes and instantaneous changes. Only by mastering the characteristics of clouds can we accurately identify various cloud shapes and continuously improve the level of cloud observation.

(1) Low clouds

Low clouds: cumulus, cumulonimbus, stratocumulus, stratus and nimbostratus.

Low clouds are mostly composed of tiny water droplets. The lower part of thick or vertically developed low clouds is composed of tiny water droplets, while the middle and upper parts are composed of a mixture of tiny water droplets, supercooled water droplets and ice crystals. The cloud base of low clouds is lower than the ground, generally less than 2,500 meters, which varies with seasons, weather conditions and different longitudes and latitudes.

Most low clouds may produce precipitation. Nimbostratus clouds often produce continuous precipitation, while cumulonimbus clouds produce intermittent precipitation, sometimes with heavy precipitation.

1. Cumulus Cu

Cumulus clouds have clear outlines, convex tops, flat cloud bases, and many unconnected straight spreading clouds between clouds; they are caused by low-level air convection. Clouds formed by water vapor condensing or sublimating in winter.

Cu hum cumulus clouds are in the early stages of development. The bottom of the cloud body is relatively flat. The pale cumulus clouds in the north have clear outlines and are not large in size. The top is arc-shaped and convex. The horizontal width of the cloud body is greater than the vertical width. Thickness, thin clouds are white, thick clouds have a light shadow in the middle. Because the light cumulus clouds in the south have more water vapor, the outline is not as clear as the light cumulus clouds in the north. Cumulus clouds are scattered individually or in groups in the sky, and are often seen on sunny days.

Cumulus clouds are composed of small water droplets with a diameter of 5-30 microns, while cumulus clouds in the north and the Tibetan Plateau in winter are composed of supercooled water droplets or ice crystals, and sometimes sporadic rain and snow fall.

Cumulus Fc It is composed of small water droplets of 1-15 microns. The clouds are very small and scattered in the sky. Their shapes are changeable and they are white fragments. Most of them are broken or nascent cumulus clouds.

Cu cong Cu cong Cu cong is a tall cloud with a clear outline, a flat and dark bottom, much like a tower, strong vertical development, the vertical thickness exceeds the horizontal width, and the top overlaps in an arc. Much like cauliflower.

Cumulus congestus is composed of water droplets of different sizes. Small water droplets appear between 5-50 microns in diameter; large water droplets mostly appear between 100-200 microns. When clouds develop vigorously, the updraft in the clouds can reach 10-20 meters/second. When the cloud top temperature is below -10°C, supercooled water droplets, frozen droplets, graupel and ice crystals will appear. Whenever Cumulus Congestus develops very strongly, a turban-like white cloud will appear on the top of the cloud, called a frigate cloud.

Cumulus congestus is formed by the development or merger of Cumulus congestus. When it is in its vigorous development stage, there is generally no precipitation, but light showers sometimes occur. If cumulus dense clouds develop in the early morning, it shows that the atmospheric stratification is unstable and thunderstorms will occur.

2. Cumulonimbus Cb

Cumulonimbus evolved from Cumulonimbus cloud. The cloud body is thick, large and vertically developed, much like a towering mountain, with the top of it crystallized by ice. , white, with a wool-like fiber structure. The top of the cloud gradually flattens into an anvil shape as the cloud develops. The bottom of cumulonimbus clouds looks very dark, often with drooping rain streamers or broken rain clouds.

The lower part of cumulonimbus clouds is composed of water droplets and supercooled water droplets. The middle and upper parts are composed of supercooled water droplets, frozen droplets, ice crystals and snow crystals. When they are at their most vigorous development stage, there are also graupel particles and hailstones of different sizes. There are strong rising and downdraft areas in cumulonimbus clouds. The larger updraft speed can reach 30-35 meters/second, and the normal airflow can reach 10 meters/second. The base of cumulonimbus clouds often has an uneven, roller-shaped or hanging ball-shaped cloud base.

Cumulonimbus clouds are convective clouds that have reached their peak stage. They often produce strong bursts of precipitation, accompanied by strong winds, thunder and lightning, and sometimes strong hail (called hail clouds). A tornado occurred.

Cumulonimbus bald Cb calv Cumulonimbus bald is the transitional stage of development from Cumulonimbus congestus to Cumulonimbus bristle. The top of the cloud has begun to crystallize, forming an overlapping arc shape with a blurred outline. A small amount of white, fluffy cloud filaments have appeared, but they have not yet expanded.

Mane cumulonimbus Cb cap It is the mature stage of cumulonimbus development. The top of the cloud has a white hairy fiber structure, and has expanded into a horsehair shape. It is called a mane cumulonimbus or anvil-shaped cumulonimbus. Rain clouds, the base of the clouds is dark and chaotic.

3. Stratocumulus Sc

The size of the cloud body is uneven, the thickness is uneven, and the shape is greatly different. There are strips, sheets or masses, and are gray-white or dark gray. Thin stratocumulus clouds allow you to see where the sun is, while thick stratocumulus clouds are darker. Stratocumulus clouds are distributed differently in the sky, some are arranged in rows or waves, and some are arranged very irregularly.

The thickness of stratocumulus clouds is between 100 meters and 2000 meters, and they are composed of water droplets with a diameter of 5-40 microns. Stratocumulus clouds in winter and over plateau areas are composed of supercooled water droplets, ice crystals, and snow crystals.

Stratocumulus clouds are formed under normal weather conditions by the condensation of water vapor due to wave motion and turbulent mixing in the atmosphere. Sometimes formed by local radiative cooling.

The cloud base of stratocumulus clouds is low, and short-term rainfall often occurs when the cloud layer develops thickly, and snowfall occurs in winter.

Phosphoric stratocumulus Se tra The cloud body is thin, gray-white, relatively neatly arranged, and the edges of the photic stratocumulus clouds are brighter. There are obvious gaps between the clouds, and the positions of the sun and the moon can be distinguished. If there are clouds above the stratocumulus, it can also be seen.

Stratocumulus obscurus Sc op The clouds or strips of obscuring stratocumulus are relatively dense, thick, dark gray, and seamless. Most of the clouds can block the sun and moon. Stratocumulus clouds have obvious undulations at the base of the clouds, filling the sky and sometimes producing precipitation.

Cumulus stratocumulus Sc cug The cloud body is a flat long strip, off-white, dark gray, with cumulus characteristics on the top. It is formed by the expansion and elongation of receding cumulus clouds or cumulonimbus clouds; sometimes it is formed by the direct impact of heat dissipation from the ground and rising air in the evening. The emergence of cumulus stratification shows that convection weakens and tends to stabilize, and sometimes sporadic light rain falls.

Stratocumulus Sc cast is a cloud in the shape of an elongated strip with a flat bottom and one or several cloud castles protruding from the top, but with different heights and a tendency to continue to develop. The viewing angle width of the cloud is greater than 5°. From a distance it looks like a castle or long sawtooth. Castellated stratocumulus clouds are formed when strong updrafts break through the stable air layer in local areas and then continue to develop. If the local water vapor conditions are good and the vertical airflow continues to strengthen, it will be conducive to the development of cumulonimbus clouds, indicating that there will be thunderstorms in the local area.

Se lent lenticular stratocumulus clouds are mostly thick in the middle and thin at the edges. They form pods and spindle-shaped clouds under the influence of terrain affecting airflow to form standing waves, with distinct individuals and distribution. In the sky, the cloud viewing angle width is 5°-30°.

4. Stratus Clouds St

The clouds are relatively uniform and curtain-shaped, gray-white, like dense fog. The cloud base is low but not grounded, often covering mountains and high-rise buildings.

Stratus clouds are composed of water droplets or supercooled water droplets with a diameter of 5-30 microns. Stratus cloud thickness is generally between 400-500 meters.

Stratus clouds are formed when water vapor condenses or is lifted by fog due to strong radiation cooling or turbulent mixing at night under stable atmospheric conditions. Stratus clouds often gradually increase in temperature after the sun rises, the stable layer is destroyed, and stratus clouds gradually dissipate. Stratus clouds sometimes cause drizzle and light snowfall in winter.

Fractal stratus cloud Fs It is a stratus cloud formed by the lifting of broken clouds or radiation fog during the gradual dissipation of stratus clouds. The shape is changeable and is gray or off-white. When the stratus cloud appears, it will be a sunny day. .

5. Nimbostratus Ns

Nimbostratus cloud base is very low and the cloud layer is very thick. The general thickness is 4000-5000 meters. It can block the sun and moon and is dark gray. Broken rain clouds often appear at the bottom. Nimbostratus clouds cover a large area and often fill the sky.

The middle and lower parts of the clouds are composed of water droplets and supercooled water droplets. The central part of nimbostratus clouds in northern and plateau areas is composed of supercooled water droplets, ice crystals, and snow crystals.

Nimbostratus clouds often appear in warm front cloud systems and sometimes in other weather systems. They are formed by the sliding and adiabatic cooling of moist air systems. Nimbostratus clouds often produce continuous rainfall. It snows in winter in the north, but snow often occurs in summer in plateau areas. The farmer's proverb "The sky is covered with gray cloth, and the rain is steady and continuous" refers to the precipitation of nimbostratus clouds.

Nimbus Fn The cloud base is very low, usually only 50-400 meters. The clouds are scattered and broken, with changeable shapes and fast movement. They are gray or dark gray and often appear in nimbostratus clouds. Rain clouds or thick altostratus clouds are formed under the cloud base by evaporation of raindrops or sublimation of snow crystals, increase in humidity in the air, and condensation of water vapor under the action of turbulence.

(2) Medium clouds

Medium clouds: Altostratus clouds and altocumulus clouds.

Medium clouds are composed of tiny water droplets, supercooled water droplets, or a mixture of ice crystals and snow crystals. The cloud base height of Zhongyun is generally between 2500-5000 meters. Altostratus clouds produce more rainfall in summer and snowfall in winter. No precipitation occurs when Altocumulus clouds are thin, but rain (snow, streamers) occurs in Altocumulus clouds in plateau areas.

1. Altostratus clouds As

Altostratus clouds are gray or off-white cloud curtains. The cloud layer is mostly between 1,500 and 3,500 meters thick, and striped structures often appear at the bottom of the clouds. Generally, altostratus clouds can partially or completely fill the sky.

Altostratus clouds are mostly composed of water droplets with a diameter of 5-20 microns, supercooled water droplets, ice crystals, and snow crystals (columnar, hexagonal, flaky, etc.).

Translucent Altostratus As tra The cloud layer is thin and uniform in thickness, but the top of the cloud layer is undulating. The clouds are gray-white, and the blurry outlines of the sun and moon can be observed through the clouds, as if separated by a layer of frosted glass.

Light-shielding altostratus As op The clouds are thick but relatively uniform, with uneven tops and gray or dark gray cloud bases. Alternating light and dark stripe structures can be observed at the bottom. Because the clouds are very thick, it is difficult to observe them on the ground. Less than the sun and moon.

2. Altocumulus Ac

Altocumulus clouds are smaller and have distinct individuals. The thickness and shape of the clouds are different. Thin clouds are white, and the outlines of the sun and the moon can be observed. The thick clouds are dark gray, and the outline of the sun and moon cannot be clearly seen.

The shape of Altocumulus clouds is mostly oblate, tile-like, fish-scale or wavy dense cloud strips.

The distribution in the sky is often densely arranged in rows or waves, and the viewing angle width of the clouds is 1°-5°.

Altocumulus clouds are composed of tiny water droplets or supercooled water droplets mixed with ice crystals. Whenever the sun and moon pass through thin altocumulus clouds, it is often observed that the inner blue and outer red halos, also known as blooms, are formed due to the diffraction of light by tiny water droplets or ice crystals in the altocumulus clouds.

Altocumulus clouds are formed under the saturated conditions of cold air beneath the high-altitude temperature inversion layer. The clouds are not thick, relatively stable, and rarely change, indicating a sunny day. The farmer's proverb "Clouds with tiles are harmful to the sun", "There are carp spots in the sky, and there is no need to turn over the grain to dry the sun." It means that after the appearance of such altocumulus clouds, it will be sunny. If the thickness of altocumulus clouds continues to thicken and gradually merge into layers, it will soon show that the weather will change and even precipitation may occur.

Translucent Altocumulus Ac tra The clouds are thin, white, and neatly arranged in the sky. There are gaps between the clouds, and the blue sky is visible. Sometimes there are no gaps between the clouds, and the edges are brighter. , through the edge of the cloud, the position of the sun and moon can be distinguished.

Light-blocking Altocumulus Ac op The clouds are thick and dark gray, and the clouds have merged into layers. The sun and moon cannot be identified, and sometimes trace amounts of precipitation occur.

Altocumulus lenticularis Ac lent. The cloud body is thick in the middle and thin on the edge. The cloud body is dark gray in the middle and white on the edge. It has clear outlines. It is generally in the shape of a pod or oval and is scattered in the sky. Beautiful iridescence appears whenever lenticular clouds block the light of the sun and moon.

Lenticular altocumulus clouds are formed by the standing waves formed by the influence of the mountains near the measuring station on the air flow. They often appear in sunny and windy weather.

Cumulus Altocumulus Ac cug Clouds are large or small, gray-white in color, slightly thicker in the middle, and slightly arched at the top. It is produced by the expanding evolution of receding cumulus or cumulonimbus clouds. The appearance of such clouds indicates that the weather is gradually stabilizing.

Altocumulus flocculus Ac flo are altocumulus clouds of different sizes, with a cumulus shape. The lower part of the cloud is relatively broken, much like broken cotton wool, scattered in the sky, with different heights. Off-white or gray, snow flags may appear.

Flocculent altocumulus clouds are formed when the moist air layer at high altitude is very unstable and mixed with strong turbulence. The appearance of such clouds in some areas indicates thunderstorms. There is a farmer's proverb: "If there are clouds in the morning, thunderstorms will come in the afternoon."

Ac cast Altocumulus clouds are distributed in horizontal strips at high altitudes. There are many upward bulges on the top that look like castles, and some have a sawtooth shape. The appearance of such clouds indicates that there will be unstable thunderstorm weather, and the farmer's proverb is "the castle clouds will drown people to death".