What characterizes the tropopause?

The tropopause is characterized by an abrupt change in the temperature lapse rate. This layer acts as a boundary between the troposphere, where temperature generally decreases with altitude due to the warming effect of the Earth's surface, and the stratosphere, where temperature starts to increase with altitude because of the ozone layer absorbing solar radiation.

At the tropopause, the temperature stops decreasing with height and remains relatively stable, marking the transition to the warmer stratosphere. This sharp contrast in temperature change is what defines the tropopause and is important for meteorology and aviation, as it influences weather patterns and the performance of aircraft.

Maintaining consistent pressure levels does not capture the defining characteristic of the tropopause, as pressure typically decreases with altitude but does not have the abrupt change observed in temperature. Similarly, a steady temperature throughout does not accurately describe the nature of the tropopause, since it is characterized by significant changes in temperature lapses. Lastly, the gradual decrease in temperature would apply to the troposphere itself, rather than the specific transition that occurs at the tropopause.