# How is weather formation prevented in the stratosphere?

Water diffuses from an area of high concentration to an area of low concentration.

By that principle, I would expect water from the troposphere to diffuse into the stratosphere, where water content is significantly lower than in the former. However, this is not what happens; a reason given in my textbook is as follows:

Increasing temperatures stop clouds and weather systems from reaching this height: it acts like the lid on top of a boiling pan above the active weather systems in the troposphere. $$^{1}$$

How is it that rising temperatures play a role here? Plus, the hottest region of the stratosphere (its top) isn't much hotter/colder compared to the troposphere, so a temperature gradient wouldn't be responsible, would it?

Essentially, what role does temperature play with weather "regulation" and how does it prevent weather formation & water entering the stratosphere through diffusion?

1. Pallister, John. IGCSE Environmental Management. Second ed., Oxford University Press, 2017.

• Check on 'convective stability of the atmosphere', that's the answer you are looking for.. Aug 29 at 9:26
• What is your source from the first statement? Aug 29 at 18:56
• @JeopardyTempest britannica.com/science/diffusion Aug 30 at 2:53
• "Because the temperature of the lower atmosphere (the troposphere) decreases rapidly with increasing altitude to about 15 km (about 9 miles), the upper levels of the troposphere contain little water vapour; most of the vapour is found within a few kilometres of Earth’s surface. The average relative humidity of tropospheric air is about 50 percent. Above 15 km, water vapour is essentially frozen out of the atmosphere, amounting to less than 0.1 percent of its concentration at Earth’s surface." britannica.com/science/hydrosphere/…
– f.thorpe
Aug 30 at 4:31