Why there is no rain in the stratosphere?

Answer 1

There is no rain in the stratosphere because the amount of water in the stratosphere is much lower than in the lower atmosphere, which means the condensation of water vapour which creates rain doesn't occur in the atmosphere.

Answer 2

Rain occurs in the troposphere, the lowest layer of the Earth's atmosphere, because this layer is where most of the water vapor and weather systems are located. The stratosphere, located above the troposphere, is much drier and lacks the conditions necessary for rain to form.