Why are water vapours not found in the layers above troposphere?

Water vapors are primarily found in the troposphere because it is the lowest atmospheric layer where temperature decreases with altitude, allowing for condensation and cloud formation. Above the troposphere, in the stratosphere and higher layers, temperatures increase with altitude, which inhibits the condensation of water vapor. Additionally, the lower pressure and reduced temperatures in these upper layers make it difficult for water vapor to exist in significant quantities. As a result, water vapor is mostly confined to the troposphere.