The
stratosphere () is the second major layer of
Earth's atmosphere, just above the
troposphere, and below the
mesosphere. It is
stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler higher up and warmer farther down. The border of the troposphere and stratosphere, the
tropopause, is marked by where this inversion begins, which in terms of
atmospheric thermodynamics is the
equilibrium level. At moderate latitudes the stratosphere is situated between about and
altitude above the surface, while at the
poles it starts at about altitude, and near the
equator it may start at altitudes as high as .