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 mostly horizontally. Classification, as a rule, is carried out in accordance with the speed, scale, types of forces, their causes, places of distribution. Under the influence of flows are various natural phenomena and weather. The wind contributes to the transfer of dust, seeds of plants, promotes the movement of flying animals. But how does directional airflow come about? Where does the wind blow from? What determines its duration and strength? And why do the winds blow? About this and much more - later in the article.
Classification
First of all, winds are characterized by strength, direction and duration. Gusts are strong and short-term movements (up to several seconds) of air flows. If a strong wind of medium duration (about a minute) blows, then 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, a hurricane, a storm, a storm. The duration of the winds can also be different. Some last a few minutes, for example. The breeze, which depends on the temperature difference on the relief surface during the day, can last up to several hours. The local and general circulation of the atmosphere is made up of trade winds and monsoons. Both of these types are classified as "global" winds. Monsoons are caused by seasonal changes in temperature and last up to several months. The trade winds are air masses that are constantly moving. They are due to temperature differences at different latitudes.
How to explain to a child why the wind is blowing?
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 in one place and not in another. It is enough to simply explain to the baby that in winter, for example, a cold wind blows due to low temperatures. How does this process take place? It is known that the air flow is a mass of atmospheric gas molecules moving together in one direction. A small air stream, 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, then it can cover a fairly large distance. In closed rooms, air practically does not move. And you can even forget about its existence. But if you expose, for example, a hand from the window of a movingcar, 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 take a closer look at this process.
Atmospheric pressure difference
So why does the wind blow? For children, it is better to cite a dam as an example. On the one hand, the height of the water column, for example, is three, and on the other, six meters. When the sluices are opened, the water will flow to the area where it is less. The same thing happens with air currents. Different parts of the atmosphere have different pressures. This is due to the difference in temperature. Molecules move faster in warm air. Particles tend to scatter from each other in different directions. In this regard, warm air is more discharged and weighs less. As a result, the pressure that is created in it decreases. If the temperature is lowered, then the molecules form closer clusters. Air therefore weighs more. As a result, the pressure rises. Like water, air has the ability to flow from one zone to another. So, the flow passes from the area with high pressure to the area with low pressure. That's why the winds blow.
Movement of streams near water bodies
Why does the wind blow from the sea? Consider an example. On a sunny day, the rays warm up both the shore and the reservoir. 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. BUTHere the coast heats up much faster. And the air above it is more discharged, and the pressure, respectively, is lower. Atmospheric flows rush from the reservoir to the shore - to a freer area. There they, heating up, rise up, again freeing up space. Instead, a cool stream appears again. This is how air circulates. On the beach, vacationers may occasionally feel a light cool breeze.
The meaning of the winds
Having found out why the winds blow, it should be said about the impact they have on life on Earth. The wind is of great importance for human civilization. The whirling currents inspired people to create mythological works, expanded the trade and cultural range, and influenced historical phenomena. The winds also acted as energy suppliers for various mechanisms and units. Due to the movement of air currents, sailing ships were able to travel considerable distances across 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 control of the aircraft can 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 expansion of the fire. In general, the phenomena associated with the formation of air currents affect living things in various ways.nature.
Global Effects
In many areas of the planet dominated by air masses with a certain direction of movement. In the region of the poles, as a rule, eastern winds prevail, and in temperate latitudes - western winds. At the same time, in the tropics, air currents again take an easterly direction. On the borders between these zones - the subtropical ridge and the polar front - there are so-called calm areas. There are practically no prevailing winds in these zones. Here the movement of air is carried out mainly vertically. This explains the appearance of high humidity zones (near the polar front) and deserts (near the subtropical ridge).
Tropics
In this part of the planet the 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 manifest itself on a significant scale. So, for example, the trade winds moving over the Atlantic Ocean carry dust from the African desert territories to the West Indies and parts of North America.
Local effects of air mass formation
Finding out why the winds blow, it should also be said 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 remote areas. It can be triggered by different light absorption coefficients or by differentheat capacity of the surface. The last effect is most pronounced between the water surface and land. The result is a breeze. Another local factor of importance is the presence of mountain systems.
Influence of mountains
These systems can be a kind of barrier to the movement of air flows. In addition, mountains in many cases themselves cause wind formation. The air above the hills warms up more than the atmospheric masses above the lowlands at the same height. This contributes to the formation of low pressure zones over mountain ranges and wind formation. This effect often provokes the appearance of mountain-valley atmospheric moving masses. Such winds prevail in areas with rough terrain.
Increased friction at the valley surface leads to the deviation 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 mentioned above, mountains can act as an obstacle. When bypassing 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 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. Due to the significant air velocity gradient, the flowbecomes turbulent and continues to remain so even behind the mountain on the plain at a certain distance. Such effects are in some cases of particular importance. For example, they are important for aircraft taking off and landing at mountain airfields.
