Why do the winds blow? Why does the wind arise? The value of wind in nature

The wind is a stream of air moving in a certain direction. On other planets, it is a mass of gases characteristic of their surface. On Earth, the wind moves mainly horizontally. Classification, as a rule, is carried out in accordance with the speed, scale, types of forces, their calling, places of distribution. Under the influence of the streams are various natural phenomena and weather. The wind contributes to the transfer of dust, seeds of plants, facilitates the movement of flying animals. But how does a directed air flow appear? Where does the wind blow? What determines its duration and strength? And anyway, why do the winds blow? About this and much more - later in the article.

Classification

First of all, the 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 of medium duration is blowing (about a minute), then it is called a squall. Longer air flows are called according to their strength. So, for example, a light wind blowing on the coast is a breeze. There is a typhoon, a hurricane, a storm, a storm. The duration of winds can also be different. Some last for several minutes, for example. Breeze, depending on the temperature difference on the surface of the relief during the day, can last up to several hours. Local and general circulation of the atmosphere is composed of trade winds and monsoons. Both these types belong to the category of "global" winds. Monsoons are caused by seasonal changes in temperature and have a duration of up to several months. Trade winds are air masses constantly moving. They are due to temperature differences at various latitudes.

How to explain to the child, why the wind blows?

For children at an early age, this phenomenon is of separate interest. The child does not understand where the flow of air is formed, because of what in one place he is, and in another - no. It's easy enough to explain to the kid that in the winter, for example, a cold wind is blowing because of the low temperature. How does this process happen? It is known that the air flow is a mass of gas molecules of the atmosphere, moving together in one direction. A small air flow, blowing a high-rise building, can whistle, tear off hats from passers-by. But if the mass of gas molecules has a large volume and a width of several kilometers, it can cover a sufficiently large distance. In closed rooms, air practically does not move. And its existence can even be forgotten. But if you put, for example, a hand from the window of a moving car, you can feel the skin with air flow, its strength and pressure. Where does the wind blow? Flow movement is due to the difference in pressure in different parts of the atmosphere. Let us consider this process in more detail.

The difference in atmospheric pressure

So why is the wind blowing? For children it is better to cite the example of a dam. On the one hand, the height of the water column, for example, is three, and on the other - six meters. When opening the sluices, the water will flow to the area where it is smaller. Approximately the same thing happens with air currents. In different parts of the atmosphere, the pressure is different. This is due to the difference in temperature. In warm air, the movement of molecules is faster. Particles tend to fly apart from each other in different directions. In this regard, warm air is more discharged and weighs less. As a result, the pressure that it creates is reduced. If the temperature is lowered, the molecules form closer clusters. Air, respectively, weighs more. The pressure increases. Similarly to water, air has the property of flowing from one zone to another. Thus, the flow passes from the area with increased pressure into the region with a reduced one. That's why the winds are blowing.

Movement of streams near reservoirs

Why does the wind blow from the sea? Let's consider an example. On a sunny day, the rays warm up 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 the cold layers. But the shore heats up much faster. And the air above it is more discharged, and the pressure, respectively, is lower. Atmospheric streams rush from the pond to the shore - into a freer area. There they warm up, rise up, again making room. Instead, a cool flow appears again. This is how the air circulates. On the beach, vacationers can periodically feel a slight cool breeze.

Value of winds

Finding out why the winds are blowing, it should be said about what impact they have on life on Earth. The wind is of great importance for human civilization. Vortex flows inspired people to create mythological works, expanded the commercial and cultural range, and influenced historical phenomena. Winds also acted as energy suppliers for different mechanisms and assemblies. Due to the movement of air currents, sailing vessels were able to overcome considerable distances along the oceans and seas, and balloons - across the sky. For modern aircraft, winds are of great practical importance - they allow you to save fuel and increase lift. But it should be said that air currents can also harm a person. So, for example, due to gradient wind fluctuations, control over the aircraft control may be lost. In small water bodies, rapid air currents and waves caused by them can destroy buildings. In many cases, winds contribute to an increase in the scale of the fire. In general, the phenomena associated with the formation of air currents in various ways affect the wildlife.

Global Effects

In many parts of the planet, air masses predominate having a certain direction of motion. In the region of the poles, as a rule, the eastern ones predominate, and in the temperate latitudes the western winds predominate. In the tropics, the air flows again take the eastern direction. At the boundaries between these zones - the subtropical ridge and the polar front - the so-called quiet areas are located. Prevailing winds in these zones are practically absent. Here the air movement is carried out mainly vertically. This explains the occurrence of zones of high humidity (near the polar front) and deserts (near the subtropical ridge).

Tropics

In this part of the planet in the west direction the trade winds are blowing, approaching the equator. Due to the constant displacement of these air currents, mixing of atmospheric masses on Earth takes place. This can be manifested on a large scale. For example, trade winds moving over the Atlantic Ocean carry dust from African desert territories to the West Indies and parts of North America.

Local effects of air mass formation

Finding out why the winds are blowing, one should also say 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 triggered by different light absorption coefficients or different heat capacity of the surface. Most strongly, the last effect is manifested between the water surface and the land. The result is a breeze. Another local factor of importance is the presence of mountain systems.

The influence of mountains

These systems can represent a certain barrier to the movement of air currents. In addition, the mountains in many cases themselves cause wind formation. The air above the hills warms up more than atmospheric masses over the lowlands at the same height. This contributes to the formation of zones of low pressure over mountain ranges and wind formation. This effect often provokes the appearance of mountain-valley atmospheric moving masses. Such winds predominate in areas with rugged terrain.

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