The troposphere is the lowest layer of Earth's atmosphere, extending from the surface up to about 8 to 15 kilometers (5 to 9 miles) high, depending on the location. This layer is where most of the weather occurs, including clouds, rain, and storms. The temperature generally decreases with altitude in the troposphere, making it cooler at higher elevations. In addition to weather phenomena, the troposphere contains approximately 75% of the atmosphere's mass and most of its water vapor. It plays a crucial role in supporting life on Earth by providing the air we breathe. The boundary between the troposphere and the next layer, the stratosphere, is called the tropopause.