Isothermal knots appear because

It is because there is a pressure system in the atmospheric circulation. This system will cause the atmospheric temperature to continue to increase with increasing altitude, until reaching a height where the temperature no longer changes with increasing altitude, forming a layer with a constant temperature, which is the isothermal layer. The atmosphere above the isothermal layer is called the stratosphere. The temperature of the stratosphere changes very little, so its air density and pressure remain basically stable, forming a relatively stable atmosphere. Below the isotherm layer, as the altitude increases, the temperature gradually decreases, forming the troposphere. The existence of the isotherm layer has an important impact on atmospheric circulation, meteorological phenomena and human activities. It is an important reference information in the fields of weather forecasting and aerospace.