Relative Humidity at 925 hPa
This chart shows the relative humidity at Pa. In the forefield of a trough line
as well as at and near fronts (Jets), warmer less dense air is forced to ascend.
As the ascending air cooles, the relative humidity increases, eventually resulting
in condensation and the formation of clouds.This process is known as frontal lifting.
High relative humidity at 925 hPa - equivalent to ca. 2000 ft a.s.l. - indicates
the areas of frontal lifting and thus the active zones of the current weather.