Maarg Manthan · Topic 5.16

Types of Clouds: Cirrus, Cumulus, Stratus, Nimbus and Their Combinations

Geography › Climatology · Topic 5.16

Clouds are visible masses of tiny water droplets or ice crystals formed by the condensation of water vapour in the free air at some height above the ground. They are classed by height and form into four families: high clouds (cirrus, cirrostratus, cirrocumulus), middle clouds (altocumulus, altostratus), low clouds (stratus, stratocumulus, nimbostratus) and clouds of vertical development (cumulus, cumulonimbus). The words cirrus, cumulus, stratus and nimbus describe the form, and they combine to name every type.

5 min read · UPSC Prelims · Geography · Climatology

At a Glance

High clouds Cirrus family, above 6 km
Middle clouds Alto- family, 2 to 6 km
Low clouds Stratus family, below 2 km
Vertical clouds Cumulus and cumulonimbus
Rain clouds Nimbostratus, cumulonimbus
Exam link UPSC Prelims, Geography: Climatology

Where Does It Fit?

This topic follows the topic on dew, frost and fog and covers the condensation that forms higher in the air. It prepares for the topic on precipitation, since only some clouds produce rain. Previous topic: dew point is below 0 °C Fog Cloud…">Formation of Dew, Frost, Fog and Mist. Next topic: Types of Precipitation: Convectional, Orographic, Cyclonic, Frontal, Monsoonal.

What Is a Cloud and How Is It Classified?

In short: a cloud is a mass of tiny water droplets or ice crystals formed where rising air cools below its dew point.

A cloud forms when air rises, expands and cools to its dew point, and the vapour condenses on dust, salt and other particles, called condensation nuclei, as in Humidity, Saturation, Dew Point, Evaporation and Condensation. The droplets are so small, about 0.01 to 0.02 mm, that they float in the air. Clouds are classified by their height and form, following the system proposed by Luke Howard in 1802. The Latin names tell the type: cirrus means a curl of hair, cumulus a heap, stratus a layer and nimbus rain-bearing.

Group	Height	Clouds	Features
High clouds	Above about 6 km	Cirrus, cirrostratus, cirrocumulus	Thin, wispy, made of ice crystals; cirrus often shows an approaching warm front; cirrostratus can cause a halo around the Sun or Moon
Middle clouds	About 2 to 6 km	Altostratus, altocumulus	Greyish sheets or patches of water droplets, may bring light rain
Low clouds	Below about 2 km	Stratus, stratocumulus, nimbostratus	Grey, dull layers; stratus brings drizzle and fog-like cover; nimbostratus brings steady rain or snow
Clouds of great vertical extent	From low levels to the top of the troposphere	Cumulus, cumulonimbus	Cumulus is a fair-weather heap; cumulonimbus is a towering storm cloud with an anvil top, bringing thunder, lightning, hail and heavy rain

Which Clouds Are Most Important for Weather?

Cirrus: thin and feathery at great height; a sign of changing weather.
Cumulus: puffy, with a flat base; formed by convection on warm days; small ones mean fair weather, but they can grow.
Cumulonimbus: the thundercloud, which can be 10 to 15 km tall and brings lightning, hail, heavy showers and sometimes tornadoes, as in Thunderstorms and Tornadoes.
Nimbostratus: a thick dark layer that gives long, steady rain, typical of warm fronts, as in Air Masses, Fronts and Extra-Tropical Cyclones.
Stratus: low uniform grey layer, like fog lifted off the ground.

Satellites such as INSAT and the Indian weather satellites give images of cloud cover that forecasters at the India Meteorological Department use to track monsoon and cyclone cloud systems.

What Are the Cloud Families by Height?

Family	Height (approximate)	Types	Features
High clouds	Above 6 km	Cirrus, cirrostratus, cirrocumulus	Thin, wispy, made of ice crystals; cirrostratus can give a halo around the Sun and may warn of an approaching front
Middle clouds	2 to 6 km	Altocumulus, altostratus	Grey or bluish sheets or patches of water drops and ice
Low clouds	Below 2 km	Stratus, stratocumulus, nimbostratus	Stratus is a low grey layer; nimbostratus is thick and gives steady rain
Clouds of vertical development	Base low, tops very high	Cumulus, cumulonimbus	Cumulus are fair-weather puffs; cumulonimbus are towering storm clouds

The names combine Latin words: cirrus means curl of hair, cumulus a heap, stratus a layer and nimbus rain. Cumulonimbus, the king of clouds, can reach the top of the troposphere and produce thunderstorms, as in Thunderstorms and Tornadoes.

How Are Clouds Used in Weather Modification?

Cloud seeding is the introduction of particles such as silver iodide, sodium chloride or dry ice into suitable clouds so that they produce more rain or snow. It works only when clouds with enough moisture are already present, and its overall effect is modest and still debated by scientists, so it cannot create rain from clear skies and it is not a substitute for water management. The formation of rain from clouds is discussed in Types of Precipitation: Convectional, Orographic, Cyclonic, Frontal, Monsoonal.

Why Is This Topic Important?

Classification Cloud types asked
Hazards Fog and thunderstorms
Weather reading Clouds signal weather

What Came Next?

The next topic covers the types of precipitation: convectional, orographic, cyclonic, frontal and monsoonal. Next topic: Types of Precipitation: Convectional, Orographic, Cyclonic, Frontal, Monsoonal.

Key People and Terms

Cirrus High feathery cloud
Cumulus Heap cloud
Stratus Layer cloud
Cumulonimbus Thundercloud
Radiation fog Fog from ground cooling
Advection fog Fog from warm air over cold surface

Exam Corner

Points to Remember

Cirrus is the highest cloud.
Cumulonimbus brings thunderstorms and hail.
Nimbo means rain-bearing.
Radiation fog is common in the Indo-Gangetic plain in winter.
Fog has visibility below 1 km.

Do Not Confuse With

Fog and mist Below versus above 1 km visibility
Dew and frost Above versus below freezing
Stratus and cumulus Layer versus heap

Memory Hook

Cirrus curl high, cumulus heap, stratus spread; nimbus pours, cumulonimbus thunders.

Mains Angle

Questions ask for cloud and fog types. These points add depth.

Height High, middle, low
Fog Radiation and advection
Hazard Transport disruption

A Question You May Face

An original practice question, not a past paper question.

“Classify clouds and describe the formation of radiation and advection fog with examples.”

How to Answer

Clouds By height and form.
Fog Types.
Examples Indo-Gangetic plain, Grand Banks.
Impact Transport and health.

GS Relevance

Prelims: cloud types, heights, which cloud brings rain, cumulonimbus. GS Paper 1: atmospheric moisture and weather.

Frequently Asked Questions

How are clouds classified?

Clouds are classified by height and form into high clouds, such as cirrus, cirrostratus and cirrocumulus, above about 6 km; middle clouds, such as altostratus and altocumulus; low clouds, such as stratus and nimbostratus; and clouds of great vertical extent, cumulus and cumulonimbus.

What is cumulonimbus cloud?

Cumulonimbus is a tall, dense, towering cloud that can reach 10 to 15 km, usually with an anvil-shaped top. It forms by strong convection and brings thunderstorms, lightning, heavy rain, hail and sometimes tornadoes and squalls.

What are the four main cloud names?

The four basic words are cirrus, meaning a curl of hair, for high wispy clouds of ice; cumulus, meaning a heap, for puffy clouds; stratus, meaning a layer, for flat sheets; and nimbus, meaning rain, for rain-bearing clouds. They combine to form names such as cumulonimbus and nimbostratus.

Which clouds bring rain?

The rain-bearing clouds are nimbostratus, thick grey layers that give steady, long-lasting rain, and cumulonimbus, towering clouds that give heavy showers, thunder, lightning and sometimes hail. Other clouds such as cirrus and altocumulus rarely produce rain that reaches the ground.

What is cloud seeding?

Cloud seeding is a form of weather modification in which particles such as silver iodide or salts are scattered in clouds to supply nuclei on which droplets or ice crystals can grow, so as to increase rain or snow. Its results are limited and debated, since it needs suitable clouds in the first place.

PYQ Practice — Statement Analysis

1 Cirrus clouds are high clouds made of ice crystals.

True

They lie above about 6 km.

2 Nimbostratus clouds are fair-weather clouds.

False

They bring steady rain.

3 Cirrus clouds are high clouds made of ice crystals.