What extends from 15 or 20 km to 50 km above earth?

The region that extends from 15 or 20 km to 50 km above Earth is the stratosphere. This atmospheric layer lies above the troposphere, where most of the Earth's weather occurs, and is characterized by a temperature increase with altitude due to the presence of the ozone layer, which absorbs and scatters ultraviolet solar radiation. The stratosphere plays a crucial role in protecting life on Earth from harmful UV rays.