Common Cloud Classifications
Clouds are also called aerosols. They form when rising air cools to its saturation point. Because there are so many types and classification of clouds, it is important that they be properly identified and distinguished from each other. They play an important role in the Earth's climate and they help in balancing the basic radiation in the atmosphere, plus they are also important for producing precipitation.
It was in December 1802 when Luke Howard categorized various cloud types. He believed that the key to weather forecasting was through the changing cloud formation. He used Latin in naming the clouds and up to now, his method is considered the international standard.
Jean-Baptiste Lamarck, on the other hand, made a separate study but because he used unusual French names, it didn’t make a mark even in his native country. Heinrich Dove of Germany and Elias Loomis of the United States also proposed their own classification systems in 1828 and 1841, respectively. Neither of the two’s work became internationally accepted or recognized.
It was in 1929 when the International Meteorological Commission adopted Luke Howard’s system of classification. Originally, he had three general cloud categories: cirriform, cumuliform, and stratiform, and he later on added nimbus for clouds that produce major precipitation.
Cloud Physics or Nephology is a branch of meteorology that focuses on cloud formation, growth, and cloud precipitation. Cloud formation is very important in understanding how water vapor turns back into liquid form. Water vapor is actually water in gas form. Clouds also need a bit of dust or smoke particles and this is because water vapor needs a surface that it can cling to.
Common cloud classifications are also part of Cloud Physics. People who are interested in clouds should study it. They will learn about the Bergeron process, super-saturation, and the Kelvin-Helmhotlz instability.
Common Cloud Classifications According to Form
- Cirrus- These clouds are curly, often resembling curly hair. They are often referred to as atmospheric clouds. They usually indicate the onset of precipitation and that weather systems may deteriorate in the near future.
- Stratus- These clouds look like layers. They are horizontal with a uniform base. They are flat, featureless, and hazy. They are low-lying in altitude and are colored from white to dark gray.
- Cumulus- The term translates to heaps or piles in Latin. They are part of a bigger category of cumuliform clouds. The most intense of these clouds may be connected to severe weather phenomena like hail, tornadoes, and thunderstorms.
- Nimbus- In Latin, this word means cloud or rainstorm. This cloud produces precipitation and it falls to the ground as snow, hail, or rain.
Common Cloud Classifications by Altitude
- High Level- These clouds are at very high levels, basically above 20,000 feet or 6,000 meters upwards. They are typically white and thin in appearance. At such high elevations, these clouds are mostly made up of ice crystals. But on the horizon, they look spectacular when the sun is low. These clouds’ names have the prefix cirro.
- Mid Level- These clouds are between 6,500 to 20,000 feet or 6,000 meters above the ground. They are classified as low altitude clouds so they are composed of water droplets. However, if the temperature gets cold enough, they can be made up of ice crystals, too. Types of mid level clouds are altostratus and altocumulus.
- Low Level- These clouds generally are at a height of less than 6,500 feet. They are primarily water droplets but may sometimes contain snow and ice particles. There are two main types of low-level clouds: cumulus and stratus.
Vertically Developing Clouds
Common cloud classifications also include vertically developing clouds. These clouds are generated usually by frontal lifting or thermal convection. They can release incredible amounts of energy through condensation within the cloud. The cloud base is generally lower but it can reach great heights. They are composed of water droplets at low levels and ice crystals at high levels. They are taller more than they are wide, thus vertically developing. Examples of this type of clouds are the fair-weather cumulus and towering cumulonimbus.
The first type can be easily recognized from its defined outline and flat base. This type of cloud depends on the instability of atmospheric conditions to develop. The second type of cloud can reach up from 30,000 to 60,000 feet. This cloud continues to expand and rise because of unstable atmospheric conditions and convection. They can form a squall line, which is a line of cloud towers.
Other Cloud Types
- Wall cloud is when a cloud lowers and forms the rain-free base of a strong thunderstorm. Some may show cyclonic rotation that may lead to a tornado and strong upward motion. Other wall clouds are essentially harmless.
- Shelf cloud is a low, sometimes wedged and horizontal cloud associated with the beginnings of a gust front or potentially strong winds.
- Fractus are also known as scud. These clouds are cumuliform elements that are not associated with large thunderstorms.
- Mammatus are ominous-looking clouds but are really harmless. These are often seen after the worst of a storm has passed.
- Contrail is also known as the condensation trail. It often resembles the tail of a kite. They are man-made, as they are aircraft engine paths.
- Pileus clouds or skullcap clouds are often attached to a growing cumulus tower or a mountaintop.
Is Fog also considered a Cloud?
Common cloud classifications focus on altitude and appearance. Fog is considered a separate type of cloud, but it is distinct because it is low-lying. It is a collection of ice crystals and water droplets suspended near the Earth’s surface or in the air, and fog moisture is generated locally. It is usually sourced from nearby lakes, oceans, marshes and moist grounds. Fog starts to form when liquid vapor condenses and turns into minute liquid droplets. There are actually many types of fog: radiation, advection, ground, sea smoke, valley, hills, frozen, precipitation, artificial, and hail fog. The most common is radiation fog, which forms during the night but do not last until sunrise.