the outermost layer of the Earth's atmosphere, in which temperature increases with height.

The outermost layer of the Earth's atmosphere, where temperature increases with height, is known as the thermosphere. In this layer, the air is extremely thin, and temperatures can reach very high levels, often exceeding 2,500 degrees Celsius (4,500 degrees Fahrenheit) or more. This temperature increase occurs because the few gas molecules present absorb significant amounts of solar radiation. The thermosphere also contains the ionosphere, which is important for radio communication and reflects radio waves back to Earth.

Below the stratosphere is the troposphere. The troposphere is the lowest layer of Earth's atmosphere and extends from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles) in altitude, depending on geographic location and weather conditions. This layer contains most of the atmosphere's mass, including water vapor and air, and is where weather phenomena occur. In the troposphere, temperature generally decreases with altitude, which is in contrast to the stratosphere above, where temperature begins to increase with height.

Above the stratosphere is the mesosphere. The mesosphere extends from about 50 kilometers (31 miles) to approximately 85 kilometers (53 miles) above the Earth's surface. In this layer, temperatures decrease with altitude, reaching the coldest temperatures in the Earth's atmosphere, which can drop to around -90 degrees Celsius (-130 degrees Fahrenheit). The mesosphere is where most meteorites burn up upon entering Earth's atmosphere due to friction with the air. Above the mesosphere is the thermosphere, which features a temperature increase with height.