Clouds are formed due to the condensation of water vapour in the atmosphere. They are visible aggregations of tiny water droplets or ice crystals suspended in the air. The process of condensation occurs when warm, moist air rises, cools, and reaches a point where it can no longer hold the moisture, causing it to condense into these visible cloud formations.
CLOUDS FORMATION
- Cloud formation is indeed a fascinating process involving the transformation of invisible water vapour into visible water droplets or ice crystals.
- Water vapour and aerosol particles, such as salt and dust, are constantly present in the air, frequently colliding with each other.
- When the air cools, the water vapour condenses, sticking to these aerosol particles.
- This condensation process continues as larger water droplets gradually form around the aerosol particles.
- As more water droplets join together, clouds begin to develop.
- This cloud formation typically happens when the air reaches a state of saturation, unable to hold any more water vapour.
- This saturation leading to condensation can occur in two ways: either an increase in the water content in the air, such as through evaporation or when the air is cooled to its dew point, the temperature at which condensation initiates.
- The warmer the air, the more water vapour it can hold.
- However, as the air rises and subsequently cools, its capacity to retain water vapour decreases, leading to condensation and the creation of clouds.
- The altitude at which the dew point is reached and clouds form is termed the condensation level.
FACTORS LEADING TO CLOUD FORMATION
Cloud formation can be attributed to various factors and processes. Here are five significant mechanisms contributing to the creation of clouds:
- Surface Heating: The sun’s heating of the Earth’s surface warms the air in direct contact with it, causing it to rise. These rising air columns, often known as thermals, lead to the development of cumulus clouds.
- Topography or Orographic Forcing: The landscape’s features, like mountains or hills, can influence cloud formation. When air is compelled to ascend over topographical barriers, it cools as it rises, generating layered clouds.
- Frontal Systems: Clouds form as a result of warm air ascending over a mass of cold, dense air along frontal boundaries. These fronts delineate the boundary between warm, moist air and cooler, drier air, leading to various cloud formations.
- Convergence: Airstreams flowing from diverse directions converge, compelling the air to ascend where they meet. This convergence can give rise to cumulus clouds and showery weather conditions.
- Turbulence: Sudden changes in wind speed at different altitudes can create turbulent eddies in the air, also influencing cloud development.
Each of these processes contributes uniquely to the formation and variety of clouds observed in the atmosphere.
TYPES OF CLOUD
Clouds come in various forms, each associated with different altitudes and characteristics. Here are the main cloud types based on their altitudes:
High Altitude Clouds:
- Cirrus Clouds: High-level clouds located above 20,000 feet, primarily composed of ice crystals, appearing thin, streaky, and white, sometimes exhibiting colors during specific sunlight angles.
- Cirrostratus Clouds: Thin and sheet-like clouds at high altitudes, often covering the sky and causing halos around the sun or moon.
- Cirrocumulus Clouds: High-altitude clouds seen as small, white patches or ripples.
Middle Altitude Clouds:
- Altostratus Clouds: Clouds at middle levels between 6,500 and 20,000 feet, composed of liquid water droplets, ice crystals, or a combination, and often appear as gray or blue-gray sheets covering the sky.
- Altocumulus Clouds: Mid-level clouds seen as rounded masses or rolls.
Low Altitude Clouds:
- Stratus Clouds: Low-level clouds that develop horizontally in layers or sheets, creating overcast or fog-like conditions.
- Cumulus Clouds: Low-level clouds that form vertically, often associated with fair weather, appearing as fluffy, white clouds with a flat base.
Vertical Clouds:
Cumulonimbus Clouds: Clouds extending from lower to higher altitudes, created through thermal convection or frontal lifting, often leading to thunderstorms and heavy rain.
Fog:
Fog is a cloud-like layer of stratus clouds close to or on the ground, significantly reducing visibility, often occurring within 60 metres.
Understanding the different cloud types aids in weather observation, as their appearance can offer insights into upcoming weather patterns. Each cloud type is associated with specific altitudes and characteristics, providing valuable information about atmospheric conditions.
CIRRUS CLOUD
- Cirrus clouds are distinct, detached cloud formations characterised by their delicate, white filaments, appearing as patches or narrow bands.
- They often possess a fibrous or silky sheen, with a transparent quality contingent upon the separation of their ice crystals.
- Composed solely of ice crystals, Cirrus clouds typically do not significantly reduce the brightness of the sun when they pass in front of it.
- However, exceptionally thick Cirrus formations may obscure the sun’s light and its outline.
- During specific times such as before sunrise or after sunset, Cirrus clouds exhibit striking colours like bright yellow or red.
- These clouds tend to be illuminated earlier than other cloud types, staying visible even after sunset and fading to grey later on.
- When Cirrus clouds are near the horizon, their yellowish hue results from the increased distance and the thickness of air traversed by the rays of light.
CIRROSTRATUS
- Cirrostratus clouds are characterised by their translucent, whitish appearance, often resembling a veil with either a fibrous or smooth texture.
- These extensive sheets of clouds tend to eventually cover the entire sky.
- One way to distinguish a milky veil of fog or a thin stratus cloud from cirrostratus is through the halo phenomena produced by the sun or the moon.
- Cirrostratus clouds commonly generate halos around the sun or moon, distinguishing them from other similar-looking cloud types.
- The presence of a halo effect can often indicate the presence of cirrostratus clouds.
CIRROCUMULUS
- Cirrocumulus clouds are typically thin, white patches, sheets, or layers in the sky, often not casting shadows.
- They are composed of small elements that can appear in the form of regularly arranged grains or ripples.
ALTOSTRATUS
- The cloud type you’re describing matches the characteristics of Altostratus clouds. Altostratus clouds often appear as gray or bluish sheets or layers in the sky.
- They can be striated or fibrous and tend to cover the sky partially or completely.
- These clouds are thin enough to allow some sunlight through, giving the impression of viewing the sun through ground glass.
- Unlike cirrostratus clouds, they do not produce a halo effect around the sun or moon, and they also do not permit the shadows of objects on the ground to be visible.
- Altostratus clouds are typically found in the mid-levels of the atmosphere.
ALTOCUMULUS
- The cloud type you’re describing corresponds to Altocumulus clouds.
- Altocumulus clouds typically appear as white and/or grey patches, sheets, or layers in the sky.
- They can be made up of laminae (plates), rounded masses, or rolls, and may have fibrous or diffuse edges.
- One distinguishing feature of Altocumulus clouds is their ability to create a colourful optical effect known as a corona.
- When a thin, semi-transparent section of altocumulus clouds passes in front of the sun or moon, a corona, a coloured ring or halo, becomes visible.
- This optical phenomenon features a ring with red on the outer edge and blue toward the centre. Coronas tend to appear within a few degrees of the sun or moon when these types of clouds are present.
NIMBOSTRATUS
- Nimbostratus clouds are known as continuous rain clouds, formed by thickening Altostratus clouds.
- These clouds often appear as a dark grey, dense layer diffused by falling rain or snow.
- They are typically thick enough to completely obscure the sun.
- Nimbostratus clouds extend from higher levels into lower altitudes as precipitation continues, gradually merging with low-level clouds.
- They often bring extended periods of steady precipitation, creating overcast and gloomy conditions.
STRATOCUMULUS
- Stratocumulus clouds are typically grey or whitish in colour, appearing as patches, sheets, or layers.
- They often exhibit dark tessellations, resembling a honeycomb or mottled appearance, which can be in the form of rounded masses or rolls.
- These clouds usually do not display fibrous elements, except for virga (precipitation that evaporates before reaching the ground).
- Stratocumulus clouds may or may not be merged and are commonly found at lower to middle altitudes.
STRATUS
- Stratus clouds typically form a uniform, often grey, cloud layer that can create drizzle, ice prisms, or snow grains if sufficiently thick.
- When the sun is visible through this type of cloud, its outline remains distinguishable, indicating a diffuse transmission of light.
- As Stratus clouds dissipate or break up, they can reveal patches of blue sky, offering a visual contrast between the clear areas and the remaining cloud cover.
- This cloud type often appears at low altitudes and tends to create overcast or gloomy conditions.
CUMULUS
- These clouds appear as detached, usually dense formations with distinct vertical development, forming rising mounds, domes, or towers, often resembling the shape of a cauliflower, with bulging upper parts.
- The sunlit portions of these clouds often display a brilliant white colour, while their bases appear relatively dark and have a horizontal orientation.
CUMULONIMBUS
- The cloud being described is a Cumulonimbus cloud, often referred to as a thunderstorm cloud.
- These clouds are heavy and dense, resembling a mountain or a towering structure.
- Their upper portions usually exhibit a smoothed, fibrous, or striated appearance and often display a flattened, anvil-like or plume-like shape.
- Cumulonimbus clouds frequently have very dark bases and are accompanied by low, ragged clouds underneath, which may or may not merge with the base.
- These clouds are known for producing hail and are often associated with tornadoes, creating turbulent and severe weather conditions.
(FAQs) about cloud formation, types, and their characteristics:
Q: How are clouds formed?
A: Clouds form due to the condensation of water vapour in the atmosphere. Warm, moist air rises, cools, and reaches a point where it can no longer hold the moisture, leading to the condensation of water droplets or ice crystals that create visible cloud formations.
Q: What are the main mechanisms contributing to cloud formation?
A: Several factors lead to cloud development, including surface heating, topography, frontal systems, convergence, and turbulence. Each process plays a unique role in forming various cloud types by influencing the rising and cooling of air.
Q: What types of clouds exist, and how are they categorised?
A: Clouds are categorised based on their altitudes. There are high-altitude clouds, middle-altitude clouds, low-altitude clouds, vertical clouds, and fog, each with distinct characteristics based on their altitude and appearance in the sky.
Q: What are Cirrus clouds, and how are they different from Cirrostratus and Cirrocumulus clouds?
A: Cirrus clouds are high-level clouds primarily composed of ice crystals, appearing thin, streaky, and white. Cirrostratus clouds are thin and sheet-like, often covering the sky and causing halos around the sun or moon, while Cirrocumulus clouds are small, white patches or ripples found at high altitudes.
Q: How are Altostratus and Altocumulus clouds distinguished, and what optical effect can Altocumulus clouds produce?
A: Altostratus clouds are mid-level clouds appearing as grey or blue-grey sheets, not producing halos or permitting the visibility of ground shadows. Altocumulus clouds manifest as patches or layers, sometimes with fibrous or diffuse edges, and can produce a corona, a coloured ring or halo, when seen around the sun or moon.
Q: What are Nimbostratus clouds, and how are they related to low-level clouds?
A: Nimbostratus clouds are continuous rain clouds formed from thickening Altostratus clouds, typically appearing as dark, dense layers diffused by rain or snow. These clouds often merge with low-level clouds as precipitation continues.
Q: What are the characteristics of Cumulus and Cumulonimbus clouds?
A: Cumulus clouds appear as distinct, dense formations with vertical development, resembling cauliflower-shaped mounds. Cumulonimbus clouds, known as thunderstorm clouds, resemble towering structures with very dark bases, often producing hail and tornadoes.
In case you still have your doubts, contact us on 9811333901.
For UPSC Prelims Resources, Click here
For Daily Updates and Study Material:
Join our Telegram Channel – Edukemy for IAS
- 1. Learn through Videos – here
- 2. Be Exam Ready by Practicing Daily MCQs – here
- 3. Daily Newsletter – Get all your Current Affairs Covered – here
- 4. Mains Answer Writing Practice – here
