the lowest layer of the Earth's atmosphere, where most cloud formations and weather occur.

The lowest layer of the Earth's atmosphere is called the troposphere. It extends from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles) in altitude, depending on the location (higher at the equator and lower at the poles). The troposphere is where most of the Earth's weather takes place, including cloud formation, precipitation, and storms. The temperature generally decreases with altitude in this layer, and it is characterized by the presence of water vapor, which is essential for weather phenomena.