Clouds are made up of very light water droplets or ice crystals. These particles can float in the air. Many water droplets formed together scatter reflect sunlight and you see a white cloud, but with a dark or gray cloud, the sunlight is scattered in all directions instead of reflected. When warmer air rises through colder regions, the air cools and the moisture in the air starts to condense around nucleation points into many droplets of water. There are around 350 billion droplets of water in a cubic foot of a cloud. This high density of water vapor leads to the formation of clouds, and the resulting conditions and weather patterns lead to the many different kinds of clouds.
The different types of clouds are classified by 10 different genuses: cumulus, cumulonimbus, stratus, stratocumulus, altocumulus, altostratus, nimbostratus, cirrus, cirrocumulus, and cirrostratus. Each genus has different species and varieties, and there are also other types of specialty clouds like lenticular clouds and mammatus clouds. Contrails from planes are also a type of different cloud, formed by warm moisture from the engines.
Low Level Clouds
The following four types of clouds are all found in the lower level of the atmosphere from 0ft to about 6,500ft above the surface.
Cumulus clouds are the iconic puffy clouds that are usually scattered throughout the sky. In Latin, the word cumulus means pile. Just like when we say “accumulate,” it means things pile up. This type of cloud is formed when warm air rises carrying water vapor with it by evaporation. Cumulus clouds can be white or gray. White fluffy clouds mean no rain, but when they form into dark or gray clouds, it is going to rain.
Cumulus clouds come in four species: cumulus humilis (flat and wide), cumulus mediocris (average size), cumilis congesutus (tall and prone to precipitation), and cumulus fractus (raggedy and less bubbly in shape).
These towering, terrifying masses actually extend through all three levels of cloud formation, but their immense presence extends worryingly close to the ground in the lowest level. They are iconic for their tall plume shapes and the damaging thunderstorms and extreme weather they produce. Thunder, lightning, hail, tornadoes, and other severe weather are all usually indicative of a giant, glowering cumulonimbus overhead.
Stratus clouds look like a huge thick blanket covering the sky. These clouds are a sure sign of rain if it is warm and snow if it is cold. If stratus clouds are near the ground, they form fog. These clouds form when the weather has been cold and warmer moist air blows in. The amount of moisture in the air and the difference between warm and cold air determine how thick the cloud or fog is.
Stratus clouds can be continuous and blanketed if they are a nebulosus species, and they can also be broken up and irregular if they are a fractus species.
Stratocumulus clouds are very similar to the simple cumulus genus, but they form a more connected unit of still easily discernible fluffy clouds. They can often result in rain and precipitation. They can be thought of as a type of combination between the cumulus and stratus genuses.
There are two species of stratocumulus: stratiformis – which extend more continuously over the sky, lenticularis – which are more individual, ovular shaped clouds, castellanus which have more distinct tops.
These middle clouds are found in elevations of 6,500ft to 18,000ft above the Earth’s surface. They are similar in structure to many of the low level clouds, but they provide different properties.
These clouds share the same bubbly, lumpy shapes of cumulus clouds. They are more often seen in patches or repeated formations of rolling or patterned clouds. They can sometimes cause rain or snow depending on the temperature and conditions.
Altocumulus comes in four species. The familiar stratiformis (blanket like), lenticular (ovular, almond shapes), castellanus (unique tops), and floccus (which blanket the sky like stratiformis, but they are more jagged pieces of cloud instead of continuous formations).
Altostratus clouds are essentially stratus clouds that appear higher in elevation. They will not become fog-like or low down like stratus clouds, and instead they are very thin, wispy layers of cloud found in the mid-level of the atmosphere. They are very identifiable because they form such a continuous, blanketed layer of cloud cover higher in the sky.
When altostratus clouds begin to darken and produce precipitation they are classified as nimbostratus clouds. They share the same stratus attributes of a very continuous, blanket-like cloud formation, but they also bring precipitation. This precipitation can also turn into severe weather depending on the conditions. Nimbostratus clouds will often have a very wispy tendril-like base because of the rain and precipitation.
When clouds form at higher altitudes, they are often icier and brighter. These high clouds form from 18,000ft to 45,000ft above the Earth’s surface, and they often appear visibly much further away. The notable exception is the cumulonimbus, which is present at this high altitude, but it extends across all three levels with unique attributes.
Cirrus clouds are the thin, wispy clouds seen high in the sky. They look as if someone took a cloud, stretched it, pulling pieces off, like a cotton ball when it is pulled apart. They are thin because they are made of ice crystals instead of water droplets. A blue sky and a few cirrus clouds high in the sky, usually means it is going to be a nice day with fair weather.
They come in five species that essentially just dictate the shapes of the wispy trails of cirrus clouds: fibratus (straight soft), uncinus (hooked at the end), spissatus (thick and patchy), castellanus (unique tops), floccus (more defined spots).
Cirrocumulus still appear icy and wispy high up in the atmosphere, but they characterize like cumulus clouds with a more granulated and textured appearance in the sky.
These clouds forgo the wispy look of cirrus clouds, and instead they form almost a mist like covering of the upper atmosphere. They might appear as just a tint on the sky unless highlighted by sunlight or the moon.
About the Author
Based in Indiana, Molly Smith has been writing freelance articles since 2008. She specializes in health and beauty, literature and computer articles. Smith holds an Associate of Science degree in liberal arts with a concentration in English and communications.