Summary
Highlights
The National Weather Service measures temperature at a standard height above the ground. The sun's visible light is not absorbed by the atmosphere but hits the ground, which then re-radiates it as infrared light. This infrared light, absorbed by greenhouse gases like methane, carbon dioxide, and water vapor, is what primarily heats the air. This explains why temperatures generally decrease with increasing altitude.
The troposphere is the lowest layer of the atmosphere where all of Earth's weather occurs. As altitude increases in this layer, temperatures drop significantly, often reaching -40 to -60 degrees Fahrenheit. Airplanes fly near the top of the troposphere to avoid turbulence and reduce air resistance due to thinner air.
Above the troposphere is the stratosphere, where an oxygen molecule with three atoms (ozone or O3) absorbs ultraviolet light from the sun. This absorption heats the stratosphere, causing temperatures to rise contrary to the troposphere. This warmer layer creates a stable 'lid' above the troposphere, containing all of Earth's weather and preventing mixing with higher atmospheric layers.
The mesosphere is characterized by still thinner air, but it's dense enough to interact with interplanetary particles. As Earth plows through these particles at high speeds, their impact with the mesosphere's air causes them to slow down and burn up, resulting in meteor showers. Larger particles that survive this friction can reach lower atmospheric layers or even the ground.
The thermosphere absorbs high-energy UV light and X-rays from the sun, causing its temperature to rise to thousands of degrees. Despite these extreme temperatures, the sparse distribution of particles means it wouldn't feel hot to a person. This layer is also where the solar wind interacts with atmospheric gases, creating the beautiful phenomena of auroras.
The exosphere is the outermost layer, where the Earth's atmosphere gradually blends into the vacuum of interplanetary space. Even in this thin layer, there are still enough air molecules to cause drag on low Earth orbit objects like the International Space Station, necessitating intermittent boosts to maintain orbit. The Karman line, often considered the boundary of space, lies at the bottom of the thermosphere, where the sky transitions from blue to dark.