Basic principles of atmospheric phenomena

The weather phenomenon mainly comes from the temperature difference between different places. On a large scale, the area near the equator receives more solar energy per unit area than other areas. From a smaller scale, different lower boundaries (such as the ground and the ocean) have different solar energy absorption efficiency due to different physical properties.

Temperature difference will lead to pressure difference. If the temperature of a surface is very high, the air on the surface will be heated and expanded, the air pressure on the surface will be reduced, and the surrounding air will be replenished, so the air movement will produce wind. In addition, Coriolis force will affect the direction of air flow. Many complex weather phenomena originated from such a simple system, such as land and sea breeze.

Weather density (temperature and humidity) is the difference between one place and another. These differences may be due to the perspective of tropical sun at different latitudes at any specific position. A jet stream caused by a strong temperature difference between polar and tropical air. In the mid-latitude region of weather system, such as extratropical cyclone, jet stream is unstable. Because the axis of the earth is inclined relative to its orbital plane, sunlight is an event that occurs from different angles at different times of the year. Once in the temperature range of 40 C (100 F to-40 F) on the earth's surface. For thousands of years, the change of the earth's orbit has affected the solar energy received by the earth and its distribution, as well as the long-term climate and global climate change.

Pressure difference caused by reverse difference of surface temperature. Weather forecast is a scientific and applied technology to predict the atmospheric conditions of a country at a certain time and place in the future. Weather is a chaotic system, and some small changes in the system can affect the whole. Throughout human history, humans sometimes try to control the weather, and there is evidence that human activities (such as agriculture and industry) have inadvertently changed the weather pattern.

Studying the weather of other planets is helpful to understand the weather on earth. Jupiter's Great Red Spot is a famous landmark of the solar system and an anticyclonic storm with a history of at least 300 years. However, the weather is not limited to planets. The weather in a broad sense can include the changes of gases (gaseous and ionic elements) in the whole galaxy space, and the corona of stars keeps exploding, forming a very thin gas layer in the whole solar system. It can be said that the solar wind, the mass ejection of the sun, is also a kind of weather in the solar system. Meteorology began in the late19th century. Before the balloon first reached the altitude of 16 km, meteorological observers could only rely mainly on what they could know from the ground. Most of these materials are qualitative. Aristotle's masterpiece Meteorology (written about 350 BC) was a masterpiece of that era. It was not until about 2000 years after Aristotle's death, that is, around 1593 that Galileo invented the thermometer, and 1643 that Torricelli discovered the principle of barometer, that the instrument was used for the first time to measure and the records were kept. The longest history is the measured value continuously recorded in Paris from 1664. The longest record in the United States has been kept in Sogdian New Haven since 1779. By comparing the weather observation data at different locations, the concept of weather system movement is obtained. 1743, Benjamin Franklin used mail to collect weather reports to track the path of violent storms. He found that although the winds along the Atlantic coast blew from the northeast, many storms arrived in Boston later than in Philadelphia. /kloc-the invention of observation network and telegraph at the beginning of the 0/9th century made it possible to obtain the benefits of weather bodies in a wide area according to the observation data obtained at the same time. It was not long before people realized that the air was moving clockwise and counterclockwise in a huge vortex, which covered a circular area with a diameter of 500- 1000 miles (805- 1609 kilometers). In the northern hemisphere, these eddies are called anticyclones and cyclones respectively, while in the southern hemisphere, they rotate in opposite directions. Between 30-60 degrees latitude, they usually move eastward, moving 500- 1000 miles (805- 1609 kilometers) every day, and moving with their own cloud system. In the 9th century, meteorologists learned that anti-cyclone areas are usually sunny areas, but in cyclone areas, there are strong winds and precipitation, and the temperature changes rapidly. Norwegian meteorologist William Pixar and his son Jacob described these characteristics quite brilliantly. 1920, they found that the change of temperature and the coming of bad weather were mainly related to the obvious dividing line of severe wind change (they called it "front"). The warm front along the center of the cyclone is warm air from the tropics. On the cold front, this warm air mass was replaced by a new round of cold air from the polar regions. This discovery provides a model for forecasters to analyze weather phenomena. If the weather changes according to a certain logical reasoning model, then mathematical calculation can be used to make a forecast. Meteorology entered a period of rapid development before and after Yennens cyclone model appeared. With the development of aviation, upper atmosphere observation has become a daily work. The aircraft itself also provides tools for measuring air pressure, temperature and humidity at higher and higher altitudes. Study the wind by observing the path of balloons released by the ground station. In 1930s, radiosonde appeared, which is an instrument that can be hung under a weather balloon to send pressure, temperature and humidity data during the ascent. Since the radar was perfected in the 1940s, the radio sounding balloon has been tracked by radio signals, which makes it possible to measure the wind force even if the sky is covered with clouds. The development of technology and equipment since the Second World War has expanded people's understanding of the atmosphere. At present, meteorological information is collected by airplanes, ocean-going ships, drifting buoys, mooring buoys and land stations. The radar tracking system measures turbulence, wind speed, air pollution and atmospheric composition. Meteorological monitoring satellites continue to look forward to global weather. So that meteorologists can find the new weather system when it is just formed. The computer evaluates the collected data and makes mathematical calculations to infer the weather conditions in the next few days or weeks. International cooperation in global weather research greatly increases the possibility of long-term forecasting.

Weather process

The development of technology and equipment enables meteorologists to study the various processes that determine the weather more accurately. Some important topics in these studies are discussed as follows: radiation is the process of energy transmission from the sun to the earth, the atmosphere and back to space in the form of electromagnetic waves. All weather phenomena are essentially caused by radiation processes. About two-thirds of the incident solar energy is absorbed by water vapor and carbon dioxide in the earth's surface and atmosphere. The remaining third is reflected back into space by the earth, atmosphere and clouds. The earth's heat income is offset by heat loss, especially through the process of water evaporation, which requires energy. The distribution of radiation energy obtained by the earth is uneven, and the energy transmitted by the earth to the atmosphere is also uneven. All air movements and weather systems are fundamentally caused by this uneven heating, which leads to the flow of heat from warm areas to cold areas. In particular, while increasing energy in the tropics, the polar regions continue to dissipate heat in winter. The climate in the polar regions is warmed by the huge wind system, which continuously transports warm air to the polar regions and colder air to the equatorial regions. Using different types of meteorological satellites, we can observe solar radiation and its influence on a global scale. Ri yun (solar halo; Solar flare is a light phenomenon formed by the refraction of sunlight when it passes through ice crystals in clouds, which surrounds the sun in a ring shape and is colored. The appearance of solar halo often indicates that the weather will change to some extent. Solar halo is a rare astronomical phenomenon. "Solar halo" includes total halo and gap halo.

When the viewing angle corresponding to the solar halo radius is between 22 and 46, people can observe the phenomenon of "solar halo" with the naked eye. The greater the ice crystal content in the cloud, the smaller the "halo" shape after sunlight refraction, and the more obvious the halo, which is convenient for people to observe; On the other hand, a "solar halo" cannot be formed. Or even if it is formed, it cannot be observed clearly on the ground.