Other answers have already mentioned a lot of reasons why the sky is so big that you can’t fly casually~ Let’s talk about a practical example to understand the impact of natural conditions~ In this example, the planes are crowded in an “air corridor” over the Atlantic Ocean. in. Secret fear warning ahead! Today’s wind is very noisy! Why is this “gale” noisy? Can actually affect the choice of route! 1. The “highway” in the sky, it is Ta that makes the flight faster. It starts with the discovery of meteorologists. Japanese meteorologists Oishi and Saburo discovered a “highway” in the sky, which allows planes to travel faster and with greater capacity. △Oishi and Saburo｜Between 1923 and 1925, Oishi and Saburo used weather balloons to track their positions and speeds, and made nearly 1,300 observations of what he called high air currents, and made new discoveries. △ The rapid flow path from Japan to the United States. In a series of observation experiments on high air currents, Oishi and Saburo observed that the meteorological balloon would enter an area with extremely fast wind speed when it reached an altitude of about 10,000 meters. Weather balloons can fly at speeds of up to 300 kilometers per hour in this area and can reach the United States in about 3 days. Unfortunately, because the results were published in Esperanto (a man-made language invented and created in 1887 to eliminate language barriers in human international communication), his findings were not noticed by the world, and most people did not know it at the time. The existence of “river” (later called jet stream) in the sky. △Balloon bombs. During the Second World War, Japan used these high-altitude winds to launch thousands of hydrogen balloons with bombs in an attempt to bomb the United States. According to the plan, the balloon bomb must remain at a height of 10058 meters after it is lifted off. Because only at this height can we take advantage of the eastward airflow. Hidetoshi Arakawa designed an automatic control system driven by an altimeter to discard ballast or discharge hydrogen. When the height of the balloon is lower than 10058 meters, the sandbag will automatically fall off and raise the balloon; when the height of the balloon is higher than 10058 meters, the valve of the balloon airbag will automatically discharge hydrogen gas to lower the height. In 1945, one of the bombs killed 6 people in Blaye, Oregon, including 5 children and a priest’s pregnant wife. At that time, one of the victims picked up one of the explosives without knowing it, causing the disaster, the “Blay bombing.” As early as 1931 before the Bligh bombing, the U.S. military also speculated that the rapids might exist. At that time, pilot Willie Post flew from Burbank, California to Cleveland, Ohio. The plane flew more than 2,000 miles at an altitude of 30,000 feet in just 7 hours. At lower altitudes, this kind of flight usually takes more than 12 hours. The subsequent Bligh bombing made the United States more confirm that the “river” in the sky was real. Scholars named this phenomenon a jet stream. 2. How is the jet stream formed? Now that we know the existence of rapids, how did it form? The reasons may be complicated. We know that the temperature difference in the atmosphere can produce a difference in air pressure. Together with the rotation of the earth, these factors will force the air to move around the earth, and the air flows to form wind. The so-called jet stream is a strong wind belt from west to east with a height of 8-12km and a speed of 320km per hour. The length can be thousands of kilometers, and the width can be hundreds of kilometers. Jet streams flow along the boundary between hot and cold air. Because these hot and cold air boundaries are most obvious in winter, jet streams are the strongest in winter in the northern and southern hemispheres. The rotation of the earth is an important cause of the jet stream. We can see that the rotation of the earth divides this circulation into the three units shown in the figure above. The areas near 30°N/S and 50°-60°N/S are the areas with the largest temperature changes. The greater the temperature difference between the two locations, the greater the wind. Therefore, the areas near 30°N/S and 50°-60°N/S (that is, the mid-latitude area) are also the areas with the strongest high-rise winds. The 50°-60°N/S area is the location of the polar jet, while the subtropical jet is located at about 30°N. The height of the jet stream varies from 6.4 to 12.8 kilometers, and the top speed can reach 442 kilometers per hour. The actual appearance of jets is not only caused by the rotation of the earth, but also the result of the interaction of many variables, such as the position of the high and low pressure system, cold and warm air, and seasonal changes. They meander on the earth, incline and rise in altitude/latitude, sometimes split into vortices, sometimes even disappear completely, and reappear in other places after a while.