tropopauses

The tropopause is the atmospheric boundary separating the troposphere below from the stratosphere above. It is a region of transition rather than a sharp, distinct line. In essence, it marks the point where the temperature lapse rate changes. Within the troposphere, temperature generally decreases with increasing altitude. However, as air rises and enters the stratosphere, the temperature begins to increase with altitude due to the absorption of ultraviolet radiation by ozone. The tropopause is characterized by this change in temperature gradient.

The height of the tropopause varies significantly depending on latitude and season. It is generally found at lower altitudes over the poles, typically around 7-10 kilometers, and at higher altitudes over the equator, reaching about 17-18 kilometers. This variation is largely due to differences in tropospheric thickness, which is influenced by the thermal structure of the atmosphere. Seasonal changes also play a role, with the tropopause being higher in the summer and lower in the winter in mid-latitudes.

This atmospheric layer acts as a significant barrier to vertical mixing between the troposphere and stratosphere. While the troposphere is characterized by weather phenomena such as clouds and storms, the stratosphere is much more stable. Consequently, pollutants or aerosols released into the troposphere tend to remain there, while those reaching the stratosphere can persist for much longer periods. The tropopause is thus an important factor in understanding atmospheric transport and the distribution of trace gases.