The causes of various weather and natural phenomena

How is the wind formed? Why does the atmosphere move? What drives it to move? The reason is complicated. Horizontal wind, vertical ascending and descending airflow and irregular turbulent motion all have their complicated causes. Let's talk about the cause of the wind first. Since the barometer appeared in17th century, it has provided people with the key to find the mystery of the wind after pointing out the fact that air has weight and pressure. /kloc-at the beginning of the 0/9th century, the first distribution map of air pressure and wind was drawn according to the observation data of air pressure and wind in various places. This map not only shows that the wind blows from an area with high air pressure to an area with low air pressure, but also points out that the route of the wind does not blow directly from an area with high air pressure to an area with low air pressure, but deviates to the right. 100 years, people have grasped the clue of the relationship between air pressure and wind from practice and made further exploration. Summarize a set of relatively complete theories about wind. Where does the wind blow? Why does the wind sometimes blow fast and fiercely, sometimes it is lazy and weak, and it disappears completely? This is dominated by the objective laws of contradictory movements such as high and low air pressure and cold and warm temperature in the atmosphere. People not only use this law to explain the cause of wind, but also use these laws to predict the direction of wind. How are clouds formed? People often see that the sky is sometimes blue and there are no clouds in Wan Li. Sometimes there are white clouds and sometimes there are dark clouds. Why sometimes there are clouds in the sky and sometimes there are no clouds? How are clouds formed? What is it made of? Clouds floating in the sky are made up of many tiny water droplets or ice crystals, some of which are mixed together. Sometimes there are some big raindrops and ice and snow particles, and the bottom of the cloud does not touch the ground and has a certain thickness. The formation of clouds is mainly caused by water vapor condensation. The higher the altitude, the lower the temperature and the thinner the air. On the other hand, the water surface of rivers, lakes and seas, as well as the moisture of soil, animals and plants, evaporate into the air at any time and become water vapor. After water vapor enters the atmosphere, it turns into clouds to cause rainfall, or condenses into frost dew, and then returns to the ground, permeates the soil or flows into rivers, lakes and seas. Later, it evaporates (sublimates) and then condenses (condenses) and drops. It has been going on. It contains a lot of water vapor. If the hot and humid air is lifted, the temperature will gradually decrease, and when it reaches a certain height, the water vapor in the air will reach saturation. If the air continues to be lifted, there will be excess water vapor precipitation. If the temperature there is higher than 0℃, the excess water vapor will condense into small water droplets. If the temperature is lower than 0℃, excess water vapor will condense into small ice crystals. When these small water droplets and small ice crystals gradually increase to a level that can be recognized by human eyes, it is a cloud. How is the rain formed? We already know that clouds are made up of many small water droplets and small ice crystals, and raindrops and snowflakes are also made up of them. So, how do small water droplets and small ice crystals grow bigger in the clouds? Cloud drops are all small water drops. They are mainly increased by * continuing to condense and collide with each other. Therefore, in water clouds, in order to increase the cloud droplets to the size of raindrops, it is necessary to have a thick cloud, dense cloud droplets and high water content, so as to continue to condense and grow; Secondly, there needs to be strong vertical movement in the water cloud, so as to increase the chances of multiple collisions and mergers. In a relatively thin and stable water cloud, there is not enough opportunity for cloud droplets to condense and grow, which can only cause cloudy days and is unlikely to rain. In different clouds, the distribution of cloud droplet size is different. The reason for the uneven size of cloud droplets is the transfer of water vapor in the surrounding air and the evaporation of cloud droplets. The factors that make cloud droplets grow are condensation process and collision and merger process. In the case of condensation, the size of cloud droplets is uniform, but due to the supplement of water vapor, some cloud droplets grow, and the result of merger is that larger cloud droplets continue to grow and become raindrops. Raindrops fall under the action of gravity. When there is an upward airflow, there will be an upward force acting on the raindrops to slow them down, and some small raindrops may be brought up. Only when raindrops increase to a certain extent can they fall to the ground and form rainfall. How is snow formed? As we all know, clouds are composed of many small water droplets and small ice crystals, and raindrops and snowflakes are composed of these small water droplets and small ice crystals. So, how is snow formed in water clouds? Cloud drops are all small water drops. They mainly * continue to condense and collide with each other to become raindrops. Ice cloud is made up of tiny ice crystals. When these small ice crystals collide with each other, the surface of the ice crystals will heat up, some will melt, and they will stick together and freeze again. Repeat this many times, and ice crystals will increase. In addition, there is water vapor in the cloud, so ice crystals can also condense and continue to grow. However, ice cloud is generally very tall. There is not much water vapor, the condensation growth is slow, and there are not many chances of collision, so it cannot grow to a large extent to form precipitation. Even if it causes precipitation, it often evaporates in the process of falling and rarely falls to the ground. The most favorable cloud droplet growth is the mixed cloud. The mixed cloud consists of small ice crystals and supercooled water droplets. When a mass of ice crystals and water droplets in the air reach saturation, it is not saturated. At this time, the water vapor in the cloud condenses on the surface of the ice crystals, while the supercooled water droplets are evaporating, which causes the ice crystals to "absorb" the water vapor from the supercooled water droplets. In this case, ice crystals will grow rapidly. Besides, supercooled water is very unstable. When it touches it, it will freeze. Therefore, in mixed clouds, supercooled water droplets will freeze when they collide with ice crystals. Make it grow rapidly. When small ice crystals grow up and overcome the resistance and buoyancy of air, they will fall to the ground, which is snow. In early spring and late autumn, the air near the ground is above 0℃, but this layer of air is not thick and the temperature is not very high, which will make the snow fall to the ground and melt completely. This is called "falling wet snow". Or "rain and snow fall together" This phenomenon is called "sleet" in meteorology How is the fog formed? Fog and clouds are water vapor condensates composed of small water droplets or ice crystals floating in the air, but fog is generated in the near layer of the atmosphere, while clouds are generated in the upper layer of the atmosphere. Since fog is water vapor condensation, we should look for its reason from the conditions that cause water vapor condensation. There are two reasons for water vapor saturation in the atmosphere: first, it increases due to evaporation. On the other hand, the air itself will get cold. Cooling is more important for fog. When there are condensation nuclei in the air, saturated air will condense if water vapor continues to increase or melt away. If the horizontal visibility is reduced to below 1 km by condensed water droplets, fog will form. In addition, excessive wind speed and strong disturbance are not conducive to the formation of fog. Therefore, if the water vapor is sufficient, the wind will be weak in areas that are conducive to the cooling of the lower air. Fog is most likely to occur when the atmospheric stratification is stable and there are a large number of condensed nuclei. Generally speaking, there are more opportunities to form fog in industrial areas and urban centers, because there are abundant condensation nuclei there. How is dew formed? In the early morning of warm season, the dew that people can often see on the grass, leaves and crops on the roadside does not fall from the sky. The reason and process of dewing are the same as frost. Only the temperature when it is formed is above 0℃ and above 0℃, and the temperature when air is saturated with water vapor due to cooling is called "dew point temperature". In warm seasons, when the ground objects are cooled by intense radiation at night, the temperature of the air in contact with the surface of the objects drops to the "dew point", and there will be excess water vapor precipitation. Because the temperature is above 0℃, these excess water vapor will condense into water droplets and attach to ground objects. This is dew. Dew, like frost, mostly appears on clear, windless or breezy nights. At the same time, objects that are prone to condensation are often objects with large surface area, rough surface and poor thermal conductivity. Sometimes dew will form in the middle of the night, and the temperature will continue to drop in the second half of the night, making the dew on the object freeze. It's called frozen dew. Some people classify it as frost, but its formation process is related to frost. After sunrise, the temperature rises and the dew evaporates. Dew often appears in the growing season of crops. This is beneficial to agricultural production. In summer in northern China, it evaporates quickly. When there is little rain and drought, the leaves of crops are sometimes dried by the sun during the day, but when there is dew at night, the leaves will return to their original state. People often call it "rain dew", which is the reason. How does frost form in cold season? Clods are usually covered with frost crystals. They glow in the rising sun and melt when the sun rises. People usually call this phenomenon "frosting". Looking through the calendar, from the end of 10, there is always a solar term of "first frost" every year. We have seen snow and rain, but no one has seen frost. In fact, frost didn't fall from the sky. But it is formed in the air near the ground. Frost is a kind of white ice crystal, which mostly forms at night. In a few cases, when the sun shines obliquely before sunset, it can begin to form. Usually, the frost will melt soon after sunrise. But in cold weather or shady places, it can last all day. Frost itself is neither harmful nor harmful to plants. What people usually call "freezing injury" is actually a kind of "freezing injury" at the same time. The formation of frost is not only related to the weather conditions at that time, but also related to the nature of attached objects. When the surface temperature of the object is very low, but the air temperature near the surface of the object is relatively high, there is a temperature difference between the air and the surface of the object. If the temperature difference between the surface of an object and the air is mainly caused by the radiation cooling of the surface of the object, the air will be cooled when warmer air comes into contact with the surface of a colder object, and when the water vapor is supersaturated, excess water vapor will be precipitated. If the temperature is below 0℃, excess water vapor will condense into ice crystals on the surface of the object, which is frost. Therefore, frost is always formed under weather conditions that are conducive to radiation cooling on the surface of objects.