As a result, wind arises. Cognitive experimentation lesson “Why does the wind blow?” (senior group). Human use of wind

Moving in a certain direction. On other planets it represents a mass of gases characteristic of their surface. On Earth, wind moves predominantly horizontally. Classification, as a rule, is carried out in accordance with the speed, scale, types of forces that cause them, and places of distribution. Various natural phenomena and weather are influenced by flows. Wind facilitates the transfer of dust, plant seeds, and facilitates the movement of flying animals. But how does directed air flow occur? Where does the wind blow from? What determines its duration and strength? And anyway, why do the winds blow? This and much more is discussed further in the article.

Classification

First of all, winds are characterized by strength, direction and duration. Gusts are considered to be strong and short-term movements (up to several seconds) of air currents. If a strong wind blows for an average duration (about a minute), it is called a squall. Longer air currents are named according to their strength. So, for example, a light wind blowing on the coast is a breeze. There is also a typhoon. The duration of the winds can also be different. Some last a few minutes, for example. The breeze, depending on the temperature difference on the relief surface during the day, can last up to several hours. Local and general atmospheric circulation consists of trade winds and monsoons. Both of these types fall into the category of "global" winds. Monsoons are caused by seasonal changes in temperature and last up to several months. Trade winds are constantly moving winds. They are caused by temperature differences at different latitudes.

How to explain to a child why the wind blows?

For children at an early age, this phenomenon is of particular interest. The child does not understand where the air flow is formed, which is why it is present in one place and not in another. It is enough to simply explain to your child that in winter, for example, a cold wind blows due to low temperatures. How does this process happen? It is known that the air flow is a mass of atmospheric gas molecules moving together in one direction. A small-volume air flow can whistle and rip off the hats of passers-by. But if the mass of gas molecules has a large volume and a width of several kilometers, then it can cover a fairly large distance. In enclosed spaces, air practically does not move. And you can even forget about its existence. But if you put your hand out of the window of a moving car, for example, you can feel the air flow, its strength and pressure with your skin. Where does the wind blow from? The movement of the flow is due to the difference in pressure in different parts of the atmosphere. Let's look at this process in more detail.

Atmospheric pressure difference

So why does the wind blow? For children, it is better to use a dam as an example. On one side the height of the water column is, for example, three meters, and on the other - six meters. When the floodgates open, water will flow into the area where there is less water. Roughly the same thing happens with air flows. Different parts of the atmosphere have different pressures. This is due to the difference in temperature. In warm air, molecules move faster. Particles tend to fly away from each other in different directions. Due to this, warm air is more discharged and weighs less. As a result, the pressure that is created in it decreases. If the temperature is lowered, the molecules form closer clusters. Air, accordingly, weighs more. This increases the pressure. Similar to water, air has the ability to flow from one zone to another. Thus, the flow moves from an area with high pressure to an area with low pressure. That's why the winds blow.

Movement of streams near bodies of water

Why does the wind blow from the sea? Let's look at an example. On a sunny day, the rays warm both the shore and the pond. But the water heats up much more slowly. This is due to the fact that the surface warm layers immediately begin to mix with the deeper, and therefore cold, layers. But the coast is heating up much faster. And the air above it is more rarefied, and the pressure, accordingly, is lower. Atmospheric currents rush from the reservoir to the shore - to a freer area. There they, heating up, rise upward, again freeing up space. Instead, a cool stream appears again. This is how air circulates. On the beach, vacationers can periodically feel a light cool breeze.

Meaning of winds

Having figured out why the winds blow, we should talk about the impact they have on life on Earth. Wind is of great importance to human civilization. Vortex flows inspired people to create mythological works, expanded trade and cultural range, and influenced historical phenomena. Winds also acted as energy suppliers for various mechanisms and units. Due to the movement of air currents, they were able to cover significant distances across oceans and seas, and balloons - across the sky. For modern aircraft, winds are of great practical importance - they save fuel and increase air flow. But it should be said that air currents can also cause harm to humans. For example, due to gradient wind fluctuations, control over the control of the aircraft may be lost. In small bodies of water, fast air currents and the waves they cause can destroy buildings. In many cases, winds contribute to the growth of fires. In general, phenomena associated with the formation of air currents affect wildlife in various ways.

Global effects

In many areas of the planet, air masses with a certain direction of movement predominate. In the region of the poles, as a rule, eastern winds predominate, and in temperate latitudes, westerly winds predominate. At the same time, in the tropics, air flows again take an eastern direction. At the boundaries between these zones - the subtropical ridge and the polar front - there are so-called calm areas. There are virtually no prevailing winds in these areas. Here the air movement is mainly vertical. This explains the appearance of zones of high humidity (near the polar front) and deserts (near the subtropical ridge).

Tropics

In this part of the planet, trade winds blow in a westerly direction, approaching the equator. Due to the constant movement of these air currents, the atmospheric masses on Earth are mixed. This can occur on a significant scale. For example, trade winds moving over the Atlantic Ocean carry dust from African desert areas to the West Indies and some areas of North America.

Local effects of air mass formation

When figuring out why the winds blow, we should also talk about the influence of the presence of certain geographical objects. One of the local effects of the formation of air masses is the temperature difference between not too distant areas. It can be caused by different light absorption coefficients or different heat capacity of the surface. The latter effect is strongest between and land. The result is a breeze. Another local factor of importance is the presence of mountain systems.

Mountain influence

These systems may represent some kind of barrier to the movement of air flows. In addition, mountains themselves in many cases cause wind formation. The air above the hills warms up more than the atmospheric masses above the lowlands at the same altitude. This contributes to the formation of low pressure zones over mountain ranges and the formation of wind. This effect often provokes the appearance of mountain-valley atmospheric moving masses. Such winds prevail in areas with rough terrain.

An increase in friction near the valley surface leads to a deflection of the parallel-directed air flow to the height of nearby mountains. This contributes to the formation of a high-altitude jet current. The speed of this flow can exceed the strength of the surrounding wind by up to 45%. As mentioned above, mountains can act as an obstacle. When going around the circuit, the flow changes its direction and strength. Changes in mountain ranges have a significant impact on wind movement. For example, if there is a pass in the mountain range that the atmospheric mass overcomes, then the flow passes through it with a noticeable increase in speed. In this case, the Bernoulli effect works. It should be noted that even minor changes in height cause fluctuations. Due to a significant gradient in air speed, the flow becomes turbulent and continues to remain so even behind a mountain on a plain at a certain distance. Such effects are of particular importance in some cases. For example, they are important for aircraft taking off and landing at mountain airfields.

It's something mysterious. We never see it, but we always feel it. So why does the wind blow? Find out in the article!

Wind is the movement of air masses. Although we cannot see air, we know that it is made up of molecules of various types of gases, mainly nitrogen and oxygen. Wind is a phenomenon in which many molecules move in the same direction.

Where does it come from? Wind is caused by pressure differences in the Earth's atmosphere: air from an area of ​​high pressure will move towards an area of ​​low pressure. Strong winds occur when air moves between areas with huge differences in pressure levels. Actually, this fact largely explains why the wind blows from the sea to the land.

Wind formation

Wind is the movement of air near the Earth's surface. It can be a gentle breeze or a strong storm. The strongest winds occur during events called tornadoes, cyclones and hurricanes. It is caused by changes in air, land and water temperatures. When air moves parallel to a warm surface, it heats up and rises—this leaves room for cooler masses to move in. The air “flowing” into these empty spaces is the wind. It is named by the direction it comes from, not the direction it blows.

Breezes: coastal and sea

Coastal and sea breezes are wind and weather phenomena characteristic of coastal areas. A shore breeze is a breeze that blows from land to a body of water. A sea breeze is a wind that blows from water to land. Why does the wind blow from the sea and vice versa? Coastal and sea breezes arise due to a significant difference in temperature between land and water surfaces. They can extend to depths of up to 160 km or appear as local phenomena that quickly weaken within the first few kilometers along the coastline.

From a scientific point of view...

Land and sea breeze patterns can greatly influence fog distribution and cause pollution to accumulate or disperse across inland areas. Current research into the principles of land and sea breeze circulation also includes efforts to model wind patterns as they affect energy needs (such as heating and cooling requirements) in affected areas. Wind also has an impact on weather-dependent operations (eg aircraft).

Since water has a much higher heat capacity than sand or other materials in the earth's crust, given a certain amount of solar irradiation (insolation), its temperature will rise more slowly than on land. Regardless of the temperature scale, during the daytime the temperature of land can fluctuate by tens of degrees, while that of water varies by less than half a degree. Conversely, high heat capacity prevents rapid changes in liquid temperature at night, and thus, while land temperatures can drop by tens of degrees, water temperatures remain relatively stable. In addition, the lower heat capacity of crustal materials often allows them to cool faster than the sea.

Physics of sea and land

So why is there strong wind blowing? The air above the respective surfaces of land and water is heated or cooled depending on the conductivity of these surfaces. During the day, higher ground temperatures result in warmer and therefore less dense and lighter air masses over the coast compared to those adjacent to the water surface. As warm air rises (the phenomenon of convection), cooler air moves towards the voids. This is why the wind blows from the sea, and during the day there is usually a cool sea breeze flowing from the ocean to the shore.

Depending on the temperature difference and the amount of air lifted, the sea breeze can gust at speeds ranging from 17 to 25 km per hour. The greater the temperature difference between land and sea, the stronger the land wind and sea breeze.

Why does the wind blow from the sea

After sunset, the air mass over coastal land quickly loses heat, while over water it usually does not differ much from its daytime temperature. When the air mass over the land becomes cooler than the air mass over the water, the land wind begins to blow from the land to the sea.

The stirring of warm, moist air from the ocean often results in daytime clouds over the coastline. In addition, the movement of air masses and sea breezes are often used by tourists for hang gliding. Although land and sea breezes predominate along the sea coast, they are also often recorded near large bodies of water. Coastal and sea breezes lead to increased humidity levels, precipitation and moderate temperatures in coastal areas.

Explanation for children: why the wind blows

Sea breezes are most common on hot summer days due to the unequal heating rates of land and water. During the day, the land surface warms faster than the sea surface. Therefore, part of the atmosphere above the land is warmer than above the ocean.

Now remember that warm air is lighter than colder air. As a result, he rises. This process causes cooler air over the ocean to take up space at the earth's surface to replace the rising warm mass.

However, it is worth knowing that wind is formed not only as a result of differences in temperature. Global atmospheric movements arise as a result of the rotation of the Earth. These winds group the trade winds and monsoons. Trade winds occur near the equator and move either from the north or south towards the equator. In the Earth's mid-latitudes, between 35 and 65 degrees, westerly winds predominate. They blow from west to east, and also towards the poles. Polar winds blow near the north and south poles. They move from the poles to the east or west, respectively.

Our world is full of mysteries and interesting things. Unraveling them is the task of humanity. Even greater discoveries await us, but for now we already know exactly the answer to the question of how and why the wind blows, as well as what factors determine its formation. This makes it possible to predict changes in weather conditions.

“Wind, wind! You are powerful...” - every fifth grader knows this by heart. What is your power, where does it come from, how are you born, wind-breeze-wind? Time, as elusive as you, flies and changes century after century, and people still ask the same question: “What is the wind, where does it come from?” Others answer them something, each in their own way. “The wind is born from the trees,” someone says, “the trees sway and move the air.” This version is very cute, but who rocks the trees? “Like who?” answers the hero of the story, “God!”

If this is idle curiosity, it was voiced and forgotten. The wind is blowing outside - that means it’s the way it should be. But what determines your strength and why are you sometimes light and playful, sometimes angry and cruel? This is already a serious question; it is not for nothing that the best scientific minds are constantly studying what wind is and what factors its intensity and direction depend on. Thanks to their discoveries, a person today can predict in which direction and with what force you will blow. But you don’t let yourself be fooled: isn’t the effect of surprise your favorite game?

Sometimes it seems that there are no secrets here. After all, what is wind? In short - the movement of the atmosphere. That is, the flow of air molecules with And what moves these molecules is a topic for a more detailed explanation. In places where warm air accumulates, the atmospheric pressure is low. Air heated by the sun rises to the upper layers of the atmosphere and cools there, then, according to the principle of circulation, it falls down, carrying with it an area of ​​​​high pressure. These temperature changes create atmospheric movement called wind. The greater the differences, the stronger the wind.

Why is it always windy in the mountains and on the coasts? Because in places of contrasting atmospheric pressure, the circulation of warm and cold air flows occurs continuously, only its intensity changes. This is especially noticeable on the seashore, where you, the wind, frolic day and night. This is because the sun heats the land faster, while the water column warms up slowly. The warm wind rises above the ground in streams, giving way to a cold air flow from the water. And the wind starts to blow. This is what the wind from the sea is, which blows constantly. Although no, at night the reverse movement begins: the earth cools down faster, but the sea still retains heat, and now the wind changes direction - from the shore to the sea.

You are having fun, wind, because our knowledge is too narrow. There are other hypotheses about what wind is. There is a so-called one that also characterizes the movement of air currents during the rotation of the Earth. According to the French scientist Gaspard-Gustav Coriolis, our planet rotates at a higher speed than its atmospheric layer and is deflected, creating currents. And there are also eternal, or prevailing winds, blowing along the equator and from the poles of the Earth.

They say that a person knows three percent of existence. Does he know? What do you think, wind-breeze-wind? Or we don’t need to know anything, it’s better to stick to simple knowledge: wind happens because the trees sway, and God shakes them...

What is wind? This is a complex atmospheric phenomenon that occurs under certain conditions. Why is this atmospheric phenomenon? Because the area where this phenomenon occurs is the lowest atmospheric layer - the troposphere (8-12 km altitude above the earth's surface).

The concept of wind and its features

Wind is the movement of air, and not just movement, but its movement in a horizontal direction above the earth's surface. When the pressure in different parts of the globe is different, air masses tend to be distributed over the earth's surface more evenly and fill the space where the atmosphere is not so dense.

Atmospheric pressure itself is the pressure of air on the earth's surface by the attraction of air masses towards the earth. In this case, the gravitational force acts, which holds the air near the surface of the Earth, and allows people and objects to come into close contact with the earth, and not fly into space.

Based on the above, we can conclude: the wind moves not only horizontally over the Earth’s surface, but also from an area of ​​high atmospheric pressure to an area of ​​low.

The air is heated extremely unevenly, which is partly due to the constant presence of winds on the planet.

Air masses warm up most strongly at the Equator, the central latitude of the Earth. From there the winds are distributed over the entire earth's surface.

Wind strength and speed

The wind cannot be seen, but it can be felt, for example, its strength or the speed with which the wind blows a hat off one’s head or ruffles leaves on the trees. It’s not for nothing that the verbal expression “knocked down by the wind” is sometimes used, meaning that the wind was very strong.

Wind speed is expressed in terms of “meter per second”, “kilometer per hour”, and its speed can also be expressed on a point scale.

There is a so-called Beaufort scale- a scale with twelve dimensions developed by the World Meteorological Organization to measure wind speed by the waves it creates in open water spaces (most often at sea) and the force of its impact on ground objects.

When the Beaufort scale index is “0”, the wind speed reaches about 0-0.2 m/s and is characterized by calm. The leaves of the trees do not move.

With a Beaufort scale of 4, the wind is considered moderate at a speed of 5.5-7.5 m/s. On the ground, the force of such a wind is visible as follows: a strong air flow lifts dust and debris and rolls it along the road, and also sets tree branches in motion.

A storm with wind speed on the Beaufort scale occurs at number “9”: trees on the ground begin to be uprooted and roof coverings of houses begin to collapse.

Varieties of wind

There are several types of winds as currents of air masses over gigantic areas: monsoons, trade winds, foehn, breeze, bora.

Monsoon is a wind with clearly defined periods of activity. Air masses under this name blow from land to sea in winter, and from sea to land in summer. The wind is rich in moisture. Its localization is mainly in Asia.

Passat- a type of wind that blows between the tropics. Its observation time is all year round. On a 12-point scale, this wind blows with a force of 3-4 points.

Breeze– a warm wind with less localization than, for example, a monsoon or trade wind. The breeze mainly blows at night from the shore to the sea, and during the day from the sea to the shore. The direction can change several times a day.

The movement of air above the Earth's surface in a horizontal direction is called by the wind. The wind always blows from an area of ​​high pressure to an area of ​​low pressure.

Wind characterized by speed, force and direction.

Wind speed and strength

Wind speed measured in meters per second or points (one point is approximately equal to 2 m/s). The speed depends on the pressure gradient: the greater the pressure gradient, the higher the wind speed.

The strength of the wind depends on the speed (Table 1). The greater the difference between neighboring areas of the earth's surface, the stronger the wind.

Beaufort scale— a conventional scale for visually assessing the strength (speed) of the wind in points based on its effect on ground objects or on sea waves. It was developed by the English admiral F. Beaufort in 1806 and at first was used only by him. In 1874, the Standing Committee of the First Meteorological Congress adopted the Beaufort scale for use in International Synoptic Practice. In subsequent years, the scale was changed and refined. The Beaufort scale is widely used in maritime navigation.

Direction of the wind

Direction of the wind is determined by the side of the horizon from which it blows, for example, the wind blowing from the south is south. The direction of the wind depends on the pressure distribution and the deflecting effect of the Earth's rotation.

On the climate map, the prevailing winds are shown by arrows (Fig. 1). The winds observed at the earth's surface are very diverse.

You already know that the surface of land and water heats up differently. On a summer day, the land surface heats up more. When heated, the air over land expands and becomes lighter. At this time, the air above the reservoir is colder and, therefore, heavier. If the body of water is relatively large, on a quiet hot summer day on the shore you can feel a light breeze blowing from the water, above which it is higher than above the land. Such a light breeze is called a daytime breeze breeze(from the French brise - light wind) (Fig. 2, a). The night breeze (Fig. 2, b), on the contrary, blows from land, since the water cools much more slowly and the air above it is warmer. Breezes can also occur at the edge of the forest. The breeze diagram is shown in Fig. 3.

Rice. 1. Distribution diagram of the prevailing winds on the globe

Local winds can occur not only on the coast, but also in the mountains.

Föhn- a warm and dry wind blowing from the mountains to the valley.

Bora- a gusty, cold and strong wind that appears when cold air passes over low ridges to the warm sea.

Monsoon

If the breeze changes direction twice a day - day and night, then seasonal winds - monsoons- change their direction twice a year (Fig. 4). In summer, the land quickly warms up, and the air pressure above its surface increases. At this time, cooler air begins to move inland. In winter, the opposite is true, so the monsoon blows from land to sea. With the change from the winter monsoon to the summer monsoon, there is a change from dry, partly cloudy weather to rainy.

The effect of monsoons is strongly manifested in the eastern parts of the continents, where they are adjacent to vast expanses of oceans, so such winds often bring heavy precipitation to the continents.

The unequal nature of atmospheric circulation in different regions of the globe determines differences in the causes and nature of monsoons. As a result, a distinction is made between extratropical and tropical monsoons.

Rice. 2. Breeze: a - daytime; b - night

Rice. 3. Breeze pattern: a - during the day; b - at night

Rice. 4. Monsoons: a - in summer; b - in winter

Extratropical monsoons - monsoons of temperate and polar latitudes. They are formed as a result of seasonal pressure fluctuations over the sea and land. The most typical zone of their distribution is the Far East, Northeast China, Korea, and, to a lesser extent, Japan and the northeastern coast of Eurasia.

Tropical monsoons - monsoons of tropical latitudes. They are caused by seasonal differences in heating and cooling of the Northern and Southern Hemispheres. As a result, pressure zones shift seasonally relative to the equator to the hemisphere in which it is summer at a given time. Tropical monsoons are most typical and persistent in the northern Indian Ocean basin. This is greatly facilitated by the seasonal change in atmospheric pressure over the Asian continent. The fundamental features of the climate of this region are associated with the South Asian monsoons.

The formation of tropical monsoons in other areas of the globe occurs less characteristically, when one of them is more clearly expressed - the winter or summer monsoon. Such monsoons are observed in Tropical Africa, northern Australia and the equatorial regions of South America.

Constant winds of the Earth - trade winds And westerly winds- depend on the position of the atmospheric pressure belts. Since low pressure prevails in the equatorial belt, and near 30° N. w. and Yu. w. - high, at the surface of the Earth throughout the year the winds blow from the thirties latitudes to the equator. These are trade winds. Under the influence of the Earth's rotation around its axis, trade winds deviate to the west in the Northern Hemisphere and blow from northeast to southwest, and in the Southern Hemisphere they are directed from southeast to northwest.

From high pressure belts (25-30° N and S latitude), winds blow not only towards the equator, but also towards the poles, since at 65° N. w. and Yu. w. low pressure prevails. However, due to the rotation of the Earth, they gradually deviate to the east and create air currents moving from west to east. Therefore, in temperate latitudes, westerly winds predominate.