How Wind Works: Causes, Breezes, Monsoons, and Dust Storms Explained

The work of wind shapes both the natural processes of life on Earth and human economic activity, eroding rock, transporting fine material, driving ocean currents, powering the water cycle, and supplying renewable energy.

What causes wind to form?

Wind forms because air is heated unevenly, so it is warmer in one place and colder in another. The more heated air expands, becomes lighter, and rises, while colder, denser air rushes in to take its place. This movement of air — the displacement of air masses with different temperatures — is the cause of wind.

What are breezes and why do they reverse direction?

Breezes are steady coastal winds that blow from the sea toward the shore during the day and from the shore toward the sea at night, making them a clear example of regular winds in seaside regions. By day the land heats more strongly than the water, so the air warmed above it rises as lighter air, and colder air masses from the sea move in to replace it.

At night the situation reverses: land cools faster than water, because water retains the heat it has gathered far longer. The air over the sea becomes warmer at night than the air over the land, and the wind begins to blow in the opposite direction — from the shore out to sea.

This is why fishermen set out to sea late in the evening and return to their shores early in the morning with a rich catch — sailing with a following wind both ways.

How do monsoons differ from breezes?

Monsoons of tropical countries are comparable to breezes, with the difference that they blow in the same direction — from sea to land or from land to sea — not over a single day but over a much longer period, in summer and in winter, which is why they are called summer and winter monsoons. Summer monsoons blow from the ocean, while winter monsoons blow from the land.

How strong can the wind be?

The force of the wind varies widely: it can carry not only fine dust and sand but even move pebbles several centimeters across. In the southern part of the black-earth belt, in spring — when the plowed fields are not yet covered with green shoots and rain falls relatively rarely — the wind sometimes turns into dust storms. The crimson disk of the sun is barely visible through the veil of dust.

The finest dust clogs the eyes and makes breathing difficult, and there is no escaping it: it penetrates houses even through closed windows and doors.

Dust storms occur fairly often in Northern China, Southern Mongolia, and the United States.

What are samums, the sandstorms of the desert?

Samums — the sandstorms of the African deserts — are a far more menacing natural phenomenon, and caravans on the move often perish in them. The wind carries masses of dust and fine sandy material from the central parts of the desert toward its edges. The coarser material accumulates as dune sands, while the dust rises high into the atmosphere and is carried thousands of kilometers, shrouding everything in its path in a yellow haze.

How does fine material accumulate?

Desert winds weaken when they meet winds blowing from other directions, and they then deposit their fine material. A moister climate and rainfall encourage this accumulation of fine sediment. The air usually becomes clean and clear after rain precisely because it is freed of dust — dust invisible to the eye yet significant enough to reduce the visibility of distant objects.

In China, this fine-grained material — yellow earth, or loess — forms powerful layers, in places up to 100 meters thick. Loess covers vast areas and, despite its scarcity of humus, is remarkably fertile because it contains the mineral substances plants need for life.

Loess holds enormous economic importance in China as the foundation of agriculture, which is why yellow is the favorite color of the Chinese people. Loess is composed mainly of the finest particles of quartz, feldspar, clay, limestone, and mica. In the dry season loess kicks up heavy dust on the roads, and after rain it turns into sticky mud.

The origin of loess is tied to the activity of wind, which is why such rocks are called aeolian — that is, wind-formed deposits.

How do dunes and barchans form?

Along the banks of some rivers and seas the wind builds tall dunes from sand, rising like hills sometimes up to 100 meters high. In deserts the wind heaps up barchans, which differ from dunes by their characteristic crescent or half-moon shape. Their usual height is 15 to 20 meters.

Both dunes and barchans migrate — or, more precisely, drift along in the direction of the wind. On their way they bury not only plowed fields but also buildings. The speed of dune movement depends on the strength of the wind. Small dunes advance 2–3 meters a day in a strong wind. Large dunes move much more slowly — up to 20 meters a year.

To prevent the movement of dune sands, they are first fixed in place with grassy vegetation, especially by sowing grasses such as lyme grass and sand oat-grass, and only then planted with trees — chiefly pine, which thrives beautifully on sandy soils.

Barchans also cause much harm to human economic activity: they bury the plowed fields of oases, fill in wells, and choke the irrigation canals (aryks) that channel water to the barren stretches of the desert. History records many cases in which flourishing, populous cities were buried by sand, and only archaeological excavations have made it possible to reconstruct the picture of past life from numerous finds and well-preserved buildings.

How does wind work on stone?

The work of wind shows itself not only in carrying the products of weathering but also in its direct action on the obstacles it meets along the way, especially in the desert, where winds blow constantly. Windless days in the desert are extremely rare, and winds often turn into sandstorms of enormous force.

The wind drives streams of hard quartz grains that cut, drill, carve, and polish stone continuously — not merely over centuries, but over many thousands of years. The results of this work are therefore very great.

The work of wind becomes vividly expressive in the creation of such fanciful weathering forms as "aeolian mushrooms" or "aeolian tables." Their upper part is usually built of rock that is harder for the wind to work than the more yielding "stem." In loose rocks one often finds dense clusters — concretions — in the form of spheres, lenses, or other shapes.

By gradually blowing away the loose material, the wind exposes these clusters. Considerable accumulations of spheres of various sizes, as well as spheres still standing on stems, are found in the desert on the Mangyshlak Peninsula (on the eastern shore of the Caspian Sea). This well illustrates the wind's work in wearing down, grinding, and polishing stone. Desert winds gradually round off cliffs, gravel, and pebbles.

In deserts one often finds stones clearly faceted by sand on two, three, or even four sides, depending on the direction of the prevailing winds.

How does industry put the wind's work to use?

Humans put the work of wind to practical use in special sandblasting machines. These machines are used in engineering and construction to clean the surface of metal and stone by means of a jet of sand, directed by a powerful stream of air under a pressure of several atmospheres.

In this way rust, old paint, enamel, and the like are removed from metal items, while slag-like deposits that have eaten deeply into the stone are stripped from stone buildings — especially those faced with soft rock such as limestone.

What is the role of wind in the life of the Earth?

The role of wind in the life of the Earth is not limited to breaking down rocks, rounding and polishing them, transporting the crushed material, and depositing it elsewhere on the Earth's surface — it also drives the global movement of water. Under the warming of the sun, water evaporates from the oceans, seas, rivers, and various bodies of water. Evaporation also takes place through plants (read more: Transpiration in plants) and through the soil.

Water turns into vapor, which dissolves into the air. By moving masses of moist air, the wind further encourages evaporation. The water vapor lifted into the atmosphere by rising air condenses into clouds, which then fall as rain over bodies of water and continents.

Atmospheric precipitation partly enters rivers and through them returns again to the seas and oceans, and partly seeps through the soil into groundwater, which in places re-emerges at the surface as artesian springs. Water then evaporates back into the atmosphere from the soil and plants.

In this way, the wind drives the water cycle and broadens the reach of water's activity.

The work of wind can be observed constantly not only over land but also over expanses of water. By setting the surface layers of water in motion, the wind generates waves that often reach considerable size and force, leading to the destructive work of water. Rushing toward the shore, the waves undercut and erode it. Along with other causes, the wind also drives ocean currents.

Warm ocean currents flow from equatorial regions and cold ones from the polar regions. A mighty warm current is the Gulf Stream (literally "bay current" in English), which carries the warm waters of the Caribbean Sea (gulf) to the northwest toward the shores of Europe. After leaving the Gulf of Mexico it is called the North Atlantic Current.

This current has an enormous influence on the climate of Europe. It is solely thanks to the warm current that areas accessible for agriculture in Europe remain, at the corresponding latitudes in North America, barely inhabited because of the extreme harshness of the climate — for example, Baffin Island and the northern part of the Labrador Peninsula. These outlying parts of North America are, by contrast, under the influence of cold currents — the Greenland and Labrador currents.

How do people harness the energy of the wind?

People have harnessed the energy of the wind since time immemorial. A simple sail eased travel over water, and under sail bold seafarers made many remarkable discoveries and voyages around the world. The role of wind in human economic activity is no less great.

From the distant past, people learned to use the energy of wind first on simple windmills for grinding grain, and then, as they mastered technology, on special wind-power installations widely used for water supply and irrigation (read more: Water wheel), and increasingly in recent times on electric power stations.