The lowest layer of the Earth's atmosphere is called the troposphere. This is the layer closest to the Earth's surface and extends from the ground up to an average height of about 12 kilometers (7.5 miles). The troposphere contains most of the Earth's weather and is where we live and breathe. This is the layer where clouds and precipitation form, and where temperature generally decreases with altitude. The other layers of the atmosphere are the stratosphere, mesosphere, thermosphere, and exosphere, and each of them have different characteristics and functions.