Parameter: Vertical velocity at 700 hPa in hPa/h.
Description: The vertical movement of air is associated with cloud formation, precipitation, type of precipitation (negative velocity or rising air motion) or the reduction of clouds, dry an sunny weather (positive velocity or falling air motion). The vertical velocity is the result of vorticity advection and temperature advection.
Parameter: Relative Humidity at 700 hPa.
Description: 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 700 hPa - equivalent to ca. 10000 ft a.s.l. - indicates the areas of frontal lifting and thus the active zones of the current weather.
Parameter: Mean relative humidity between ca. 600 and 3000m above the ground level.
Description: This map presents the average relative humidity between about 600 and 3000m above the ground - equivalent to the atmospheric layer between 2000 and 10000ft. Although this map is by far not as important as the 'RH 700 hPa' or the 'RH 925 hPa', it gives some hints on cloud formation especially between these two pressure altitudes.