Troposphere
The lowest layer of Earth's atmosphere, extending from the surface up to the tropopause (~7 to 18 km), containing ~80% of atmospheric mass and virtually all water vapor.
Governing formula
dT / dz ≈ -6.5 °C/km (Environmental Lapse Rate)
SI unit
km (Altitude ~0 to 12 km)
In depth
Characterized by a steady temperature decrease with altitude (warmed from below by surface terrestrial thermal radiation). Driven by active convection currents, the troposphere is the primary layer where all human weather phenomena occur.
Examples in the real world
Cumulonimbus thunderstorm clouds forming convection cells that cap out at the tropopause boundary.