Meridional Transport of Water The ITCZ

Among the consequences of this general circulation are convergent and divergent flows in the surface wind leading to systematic vertical motions, es- 

The average lifetime of water vapor in the atmosphere obviously is a function of latitude and altitude. In the equatorial regions, its residence time in the atmosphere is a few days, while water in the stratosphere has a residence time of 1 year or more. Table 10-1 (Junge, 1963) provides an estimate of the average residence time for water vapor for various latitude ranges in the troposphere. Given this simple picture of vertical structure, motion, transport, and diffusion, we can proceed to examine the behavior of reactive trace substances in this dynamic milieu. However, before we can do so, it is useful to summarize briefly the overall composition of the atmosphere. 

The major gases the concentration often given as a percent (N2, O2, Ar, H2O, CO2). 

Those gases having concentrations expressed as part-per-million (Ne, He, CH4, CO). 

Gases expressed in number of atoms or molecules per cm - notably radionuclides and free radicals like OH. 

---