Is water vapor present in all layer of the atmosphere ?
Most water is in the troposphere, the lowest level of the atmosphere. This is the layer that contains most clouds, and almost all of our weather. Trace amounts of water vapor, often in the form of ice crystals, exists in the second layer, the stratosphere. If you have ever seen a "sun dog" or a "ring around the Sun", these are caused by ice crystals in the stratosphere.