. "water vapor content of atmosphere layer" . "\"Content\" indicates a quantity per unit area. \"Layer\" means any layer with upper and lower boundaries that have constant values in some vertical coordinate. There must be a vertical coordinate variable indicating the extent of the layer(s). If the layers are model layers, the vertical coordinate can be model_level_number, but it is recommended to specify a physical coordinate (in a scalar or auxiliary coordinate variable) as well." . . . . "Climate and Forecast (CF)" .