Commercial jet planes fly in the lower stratosphere to avoid turbulence. The bottom of the stratosphere is approximately 10 kilometers or 33,000 feet above ground.
The stratosphere extends to approximately 50 kilometers or 31 miles above the Earth’s surface. The troposphere, the lowest layer of Earth’s atmosphere, is where almost all weather occurs. Jet planes fly through the troposphere to reach the stratosphere, where planes fly more smoothly and experience less weather interference. The height of the troposphere varies with altitude and season. The stratosphere is dry, with little water vapor. Therefore, a small amount of clouds are found in this layer compared to the troposphere.