Clouds are visible accumulations of tiny water aerosol or water ice crystals in the Earth'south temper. Clouds differ greatly in size, shape, and color. They can appear thin and wispy, or bulky and lumpy.

Clouds commonly appear white because the tiny water aerosol within them are tightly packed, reflecting well-nigh of the sunlight that hits them. White is how our optics perceive all wavelengths of sunlight mixed together. When it's nearly to rain, clouds darken because the water vapor is clumping together into raindrops, leaving larger spaces betwixt drops of water. Less light is reflected. The rain cloud appears blackness or gray.

Clouds form when air becomes saturated, or filled, with water vapor. Warm air tin can hold more water vapor than common cold air, so lowering the temperature of an air mass is like squeezing a sponge. Clouds are the visible result of that clasp of libation, moist air. Moist air becomes cloudy with but slight cooling. With further cooling, the water or ice particles that make up the cloud can abound into bigger particles that autumn to Earth every bit precipitation.

Types of Clouds

Considering sure types of clouds are associated with certain types of conditions, information technology is possible to forecast the weather by observing and understanding these dissimilar types of clouds.

Clouds are classified into three main groups: cirrus, stratus, and cumulus.

Cirrus clouds are wispy, curly, or stringy. They are constitute high in the temper—typically college than 6,000 meters (20,000 feet)—and are usually made of water ice crystals. Cirrus clouds ordinarily betoken clear, fair weather. Their shape ofttimes indicates the direction the wind is blowing high in the temper.

Stratus clouds are horizontal and stratified, or layered. Stratus clouds can blanket the entire sky in a unmarried pattern. They usually occur close to the Earth. Stratus clouds oft form at the purlieus of a warm front, where warm, moist air is forced up over cold air. This movement produces clouds as the moist air is cooled across the entire forepart. The presence of stratus clouds usually means a chilly, overcast day. If precipitation falls from stratus clouds, it is usually in the form of drizzle or lite snow.

Cumulus clouds are large and lumpy. Their name comes from the Latin word pregnant "heap" or "pile." They tin can stretch vertically into the atmosphere upwardly to 12,000 meters (39,000 feet) loftier. Cumulus clouds are created by potent updrafts of warm, moist air. Most forms of heavy atmospheric precipitation fall from cumulus clouds. The atmospheric condition they bring depends on their height and size. The college the base of a cloud is, the drier the atmosphere and the fairer the weather condition will be. Clouds located shut to the ground mean heavy snow or rain.

Variations

Clouds are also classified co-ordinate to how loftier they are in the atmosphere and what kind of weather condition they produce.

The prefix "cirro-" refers to clouds that prevarication more than than vi,000 meters (twenty,000 feet) higher up the Earth. Cirrocumulus and cirrostratus clouds are two examples of these "high-level" clouds.

The prefix "alto-" indicates clouds whose bases are between two,000 and 6,000 meters (6,500-twenty,000 feet) above the Earth, such as altocumulus and altostratus clouds. They are considered "mid-level" clouds and are mostly made of liquid water aerosol, but can take some ice crystals in cold enough temperatures.

The prefix "nimbo-" or the suffix "-nimbus" are low-level clouds that have their bases beneath ii,000 meters (6,500 anxiety) to a higher place the Globe. Clouds that produce rain and snow fall into this category. ("Nimbus" comes from the Latin word for "pelting.") 2 examples are the nimbostratus or cumulonimbus clouds.

Nimbostratus clouds bring continuous precipitation that tin concluding for many hours. These low-level clouds are total of moisture.

Cumulonimbus clouds are as well chosen thunderheads. Thunderheads produce rain, thunder, and lightning. Many cumulonimbus clouds occur forth cold fronts, where cool air is forced under warm air. They usually shrink equally evening approaches, and wet in the air evaporates. Cumulonimbus clouds gradually go stratocumulus clouds, which rarely produce rain.

Clouds and Weather

Certain types of clouds produce precipitation. Clouds likewise produce the commodities of electricity chosen lightning and the sound of thunder that accompanies information technology. Lightning is formed in a cloud when positively charged particles and negatively charged particles are separated, forming an electrical field. When the electrical field is strong enough, it discharges a superheated commodities of lightning to the Earth. Near of what we consider to be single lightning strikes are in fact three or four separate strokes of lightning.

The sound of thunder is actually the sonic shock wave that comes when the air, heated past the lightning bolt, expands very rapidly. Thunder sometimes sounds like it comes in waves because of the time it takes the sound to travel. Because the speed of calorie-free is faster than the speed of audio, lightning will always appear before its thunder is heard.

Meteorologists measure cloud comprehend, or the amount of the visible sky covered by clouds, in units called oktas. An okta estimates how many eighths of the sky (octo-) is covered in clouds. A clear sky is 0 oktas, while a totally overcast or greyness sky is 8 oktas.

Scientists have experimented with a procedure called cloud seeding for many years. Cloud seeding aims to influence weather condition patterns. Seeds, or microscopic particles, are placed in clouds. These seeds are artificial deject condensation nuclei (CCN), which are tiny particles of dust, common salt, or pollution that collect in all clouds. Every raindrop and snowflake contains a CCN. Water or ice aerosol accumulate around CCN. Scientists hope that cloud seeding will allow people to control precipitation.

Extraterrestrial Clouds

Clouds be in outer space. Clouds on Jupiter, for instance, are divided into 3 bands in the planet's temper. The highest band, at 50 kilometers above the surface of the planet, is by and large clear.

Jupiter'south heart layer of clouds is constantly moving. These tempest clouds appear equally bands and swirls of xanthous, brown, and red. Virtually of these clouds are made of droplets of ammonia and ammonia crystals, mixed with phosphorus and sulfur. (These ammonia storms would be toxic on Earth.)

Beneath Jupiter'due south thick layer of ammonia clouds lies what some astrophysicists believe is a thin layer of water clouds. Scientists think there may be h2o clouds because bursts of lightning accept been spotted in Jupiter'south atmosphere.

Interstellar clouds, which exist in the infinite between planets and stars, are non really clouds at all. Interstellar clouds are areas where gases and plasma are dense and, sometimes, visible. Astronomers make up one's mind what elements are present in interstellar clouds by analyzing the low-cal, or radiations, that comes from them. Nearly interstellar clouds are fabricated of hydrogen, helium, and oxygen. The dusty "milk" of the Milky Mode is an interstellar deject between the stars of our galaxy.

cloud

Nosotros've looked at clouds from both sides now.

Internet Cloud
"Cloud" is sometimes used as a metaphor for the Cyberspace. The "cloud condensation nuclei" in the Internet cloud are websites around which users get together and contribute.

Contrails
Contrails (short for condensation trails) are the linear clouds left behind a jet as information technology flies through the high atmosphere. These manufactured clouds consequence when the hot air expelled from the jets engine cools and condenses in the surrounding air.

Airavata
Ancient Hindus believed the white elephant Airavata used his trunk to attain into the underworld and withdraw water. Airavata then sprayed this water into the sky, creating clouds and making precipitation possible.

accumulate

Verb

to gather or collect.

Noun

a big book of air that is mostly consistent, horizontally, in temperature and humidity.

ammonia

Noun

a gas (NH3) important to food product.

aboriginal

Describing word

very old.

astrophysicist

Substantive

person who studies the relationship betwixt affair, energy, motion, and force exterior the Globe's atmosphere.

Noun

layers of gases surrounding a planet or other celestial body.

blanket

Verb

to cover entirely.

characteristic

Noun

physical, cultural, or psychological feature of an organism, place, or object.

cirrus

Noun

sparse, high-altitude cloud.

classify

Verb

to identify or arrange by specific blazon or characteristic.

Noun

visible mass of tiny water droplets or ice crystals in Earth'southward atmosphere.

deject condensation nuclei (CCN)

Plural Noun

microscopic bits of dirt, table salt, or solid pollutant around which water vapor condenses in clouds to class raindrops.

Noun

amount of sky covered with clouds.

cloud seeding

Noun

procedure of adding chemical material to clouds in order to make it rain or otherwise command atmospheric precipitation.

contrail

Noun

(condensation trail) linear cloud left backside equally warm air ejected from a jet'south engine cools.

cumulonimbus

Noun

low-level cloud that produces rain, thunder, and lightning. Besides chosen a thunderhead.

cumulus

Noun

type of big cloud with a flat lesser and fluffy tops.

dense

Adjective

having parts or molecules that are packed closely together.

bore

Noun

width of a circle.

discharge

Verb

to eject or get rid of.

drizzle

Noun

very calorie-free rain.

Noun

tiny, dry out particles of material solid enough for wind to carry.

electrical field

Noun

area that exists between particles with opposite (positive and negative) charges.

electricity

Noun

set of physical phenomena associated with the presence and period of electric charge.

engine

Noun

machine that converts energy into power or movement.

evaporate

Verb

to change from a liquid to a gas or vapor.

Noun

overflow of a trunk of water onto land.

forecast

Verb

to predict, particularly the weather.

galaxy

Substantive

drove of stars, planets, gases, and other angelic bodies bound together past gravity.

gas

Noun

state of matter with no fixed shape that will fill whatever container uniformly. Gas molecules are in constant, random movement.

gradually

Adverb

slowly, or at a measured pace.

helium

Substantive

a light, colorless gas with the chemical symbol He.

Hindu

Noun

religion of the Indian subcontinent with many dissimilar sub-types, most based effectually the idea of "daily morality."

horizontal

Adjective

left-right direction or parallel to the Earth and the horizon.

hydrogen

Noun

chemical element with the symbol H, whose well-nigh common isotope consists of a single electron and a single proton.

ice crystal

Noun

solid ice bundled in precise molecular course.

Net cloud

Noun

cyberspace, or the network of connected facilities which store information from millions of computers connected to the internet.

interstellar cloud

Substantive

region of space where gas and plasma accrue.

jet

Noun

aircraft that moves by burning fuel.

Jupiter

Noun

largest planet in the solar arrangement, the fifth planet from the Sun.

Latin

Substantive

language of ancient Rome and the Roman Empire.

Noun

sudden electrical discharge from clouds.

metaphor

Noun

discussion or phrase used to represent something else, or an understanding of one concept in terms of another concept.

meteorologist

Noun

person who studies patterns and changes in Earth's atmosphere.

microscopic

Adjective

very modest.

Milky way

Substantive

milky way in which the World and sun are located.

nimbostratus

Noun

low-level cloud that produces continuous precipitation.

okta

Noun

unit of measurement to decide how much of the sky, measured in eighths, is covered in clouds.

overcast

Adjective

very cloudy.

oxygen

Noun

chemical chemical element with the symbol O, whose gas form is 21% of the World'due south atmosphere.

particle

Noun

modest slice of fabric.

phosphorus

Substantive

chemical chemical element with the symbol P.

Noun

large, spherical celestial body that regularly rotates around a star.

plasma

Noun

state of matter with no fixed shape and molecules separated into ions and electrons.

Noun

introduction of harmful materials into the surroundings.

Substantive

all forms in which water falls to Earth from the atmosphere.

radiations

Noun

free energy, emitted equally waves or particles, radiating outward from a source.

raindrop

Noun

drib of liquid from the atmosphere.

reflect

Verb

to rebound or return calorie-free from a surface.

table salt

Noun

(sodiumchloride,NaCl)crystalline  mineral often used as a seasoning or preservative for food.

saturate

Verb

to fill ane substance with as much of another substance equally it can take.

shock wave

Noun

moving, measurable alter in pressure level and density of a material.

snow

Noun

precipitation made of ice crystals.

snowflake

Noun

precipitation that falls equally an water ice crystal.

sonic

Adjective

having to exercise with audio or sound waves.

star

Noun

big ball of gas and plasma that radiates energy through nuclear fusion, such as the lord's day.

stratify

Verb

to divide into layers.

stratus

Noun

mid-level clouds found up to an top of about 2000 meters above the Earth.

sulfur

Noun

chemical chemical element with the symbol Southward.

sunlight

Noun

visible radiation from the sun.

thundercloud

Noun

deject filled with electricity and capable of producing thunder and lightning.

thunderhead

Noun

depression-level cloud that produces rain, thunder, and lightning. Also called cumulonimbus.

toxic

Describing word

poisonous.

underworld

Noun

mythical or legendary place for the souls of the dead.

vapor

Noun

visible liquid suspended in the air, such as fog.

vertical

Noun

upwards-down direction, or at a right angle to Earth and the horizon.

warm front end

Noun

mass of warm air that replaces a mass of common cold air.

Noun

state of the temper, including temperature, atmospheric pressure, air current, humidity, precipitation, and cloudiness.

  • Credits

    Media Credits

    The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to some other page that contains the media credit. The Rights Holder for media is the person or group credited.

    Writers

    Kim Rutledge
    Tara Ramroop
    Diane Boudreau
    Melissa McDaniel
    Santani Teng
    Erin Sprout
    Hilary Costa
    Hilary Hall
    Jeff Hunt

    Illustrators

    Mary Crooks, National Geographic Club
    Tim Gunther

    Editors

    Jeannie Evers, Emdash Editing
    Kara West

    Educator Reviewer

    Nancy Wynne

    Producer

    Caryl-Sue, National Geographic Club

    Sources

    Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Chance of Geography." Washington, D.C.: National Geographic Society.

    Last Updated

    Jan. 21, 2011

  • User Permissions

    For data on user permissions, delight read our Terms of Service. If you have questions about how to cite anything on our website in your projection or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you lot will need the folio title, URL, and the engagement you accessed the resource.

    Media

    If a media asset is downloadable, a download push appears in the corner of the media viewer. If no button appears, you cannot download or save the media.

    Text

    Text on this page is printable and tin can be used according to our Terms of Service.

    Interactives

    Whatsoever interactives on this folio can merely be played while you are visiting our website. You cannot download interactives.