Encyclopedic Entry

Farmers lose tons of topsoil to dust.

Photograph by Raymond Gehman

Dust is a collection of microscopic particles of material. Dust is heavy enough to see and light enough to be carried by the wind.

Dust can be made up of pollen, bacteria, smoke, ash, salt crystals from the ocean, and small bits of dirt or rock, including sand. Dust can also contain tiny fragments of human and animal skin cells, pollution, and hair.

When its windy outside, you can see dust particles blowing through the atmosphere. Large amounts of dust that are carried through the atmosphere by strong winds are called dust storms. Dust storms mostly occur in dry, open areas.

The Sahara Desert in Africa has many dust storms. Most Sahara dust is made of sand. Dust storms in the Sahara Desert can blow a wall of dust as high as one mile off the ground. Dust storms can make it very difficult to see and breathe.

In 1983, a dust storm covered the city of Melbourne, Australia. The deserts of Australia were experiencing drought, so sand and soil were loose. The dry conditions allowed about 50,000 tons of material to erode as dust. Melbourne had more than 1,000 tons of dust dumped on it. The dust caused so much damage that it took years of work and millions of dollars to repair.

Individual particles of dust are a major part of cloud condensation nuclei (CCN). Cloud condensation nuclei are made up of tiny pieces of solid material in clouds. CCN could be a dust storm drifting through a cloud, or an updraft with dust particles in it. Water vapor in the clouds condenses, or turns to liquid, around CCN. Invisible dust is often at the center of every raindrop.

In some areas, windblown dust settles into deposits called loess. Loess is a type of sediment that is loose and fragmented. It can be many meters deep. Loess often develops into fertile soil for agriculture because it retains water, allows many different plants to take root, and has abundant nutrients.

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

abundant

Adjective

in large amounts.

agricultural development

Noun

modern farming methods that include mechanical, chemical, engineering and technological methods. Also called industrial agriculture.

agriculture

Noun

the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

Encyclopedic Entry: agriculture

anchor

Verb

to hold firmly in place.

atmosphere (atm)

Noun

(atm) unit of measurement equal to air pressure at sea level, about 14.7 pounds per square inch. Also called standard atmospheric pressure.

bacteria

Plural Noun

(singular: bacterium) single-celled organisms found in every ecosystem on Earth.

cloud condensation nuclei (CCN)

Plural Noun

microscopic bits of clay, salt, or solid pollutant around which water vapor condenses in clouds to form raindrops.

condense

Verb

to turn from gas to liquid.

crop

Noun

agricultural produce.

Encyclopedic Entry: crop

crop rotation

Noun

the system of changing the type of crop in a field over time, mainly to preserve the productivity of the soil.

dirt

Noun

dry earth or soil.

drought

Noun

period of greatly reduced precipitation.

Encyclopedic Entry: drought

dust

Noun

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

Encyclopedic Entry: dust

Dust Bowl

Noun

(1930-1940) term for the Great Plains of the U.S. and Canada when severe dust storms forced thousands of people off their farms.

dust storm

Noun

weather pattern of wind blowing dust over large regions of land.

erode

Verb

to wear away.

farmer

Noun

person who cultivates land and raises crops.

fertile

Adjective

able to produce crops or sustain agriculture.

frequent

Adjective

often.

Great Plains

Noun

grassland region of North America, between the Rocky Mountains and the Mississippi River.

hair

Noun

thin strands of material covering the bodies of some animals, including humans.

harvest

Noun

the gathering and collection of crops, including both plants and animals.

individual

Adjective

a single thing.

liquid

Noun

state of matter with no fixed shape and molecules that remain loosely bound with each other.

loess

Noun

windblown soil or silt.

Encyclopedic Entry: loess

microscopic

Adjective

very small.

nutrient

Noun

substance an organism needs for energy, growth, and life.

Encyclopedic Entry: nutrient

ocean

Noun

large body of salt water that covers most of the Earth.

Encyclopedic Entry: ocean

particle

Noun

small piece of material.

pollen

Noun

powdery material produced by plants.

pollution

Noun

introduction of harmful materials into the environment.

Encyclopedic Entry: pollution

reduce

Verb

to lower or lessen.

rock

Noun

natural substance composed of solid mineral matter.

Sahara Desert

Noun

world's largest desert, in north Africa.

salt crystal

Noun

single particle of salt, or sodium chloride.

sand

Noun

small, loose grains of disintegrated rocks.

sediment

Noun

solid material transported and deposited by water, ice, and wind.

Encyclopedic Entry: sediment

skin

Noun

soft external covering of some animals.

smoke

Noun

gases given off by a burning substance.

updraft

Noun

rising movement of gas.

vapor

Noun

visible liquid suspended in the air, such as fog.

visibility

Noun

the ability to see or be seen with the unaided eye. Also called visual range.

wind

Noun

movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.

Credits

Media Credits

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

Writers

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

Illustrators

Tim Gunther
Mary Crooks, National Geographic Society

Editors

Kara West
Jeannie Evers

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

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

User Permissions

For information on user permissions, please read our Terms of Service.

If you have questions about licensing content on this page, please contact natgeocreative@ngs.org for more information and to obtain a license.

If you have questions about how to cite anything on our website in your project or classroom presentation, please visit our FAQ page.

Media

Some media assets (videos, photos, audio recordings and PDFs) can be downloaded and used outside the National Geographic website according to the Terms of Service. If a media asset is downloadable, a download button appears in the lower right hand corner (download) of the media viewer. If no button appears, you cannot download or save the media.

Text

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

Interactives

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.