Refer to figure.
When air encounters a high ridge of terrain, it is compelled to ascend. This upward motion, especially in unstable atmospheric conditions, can give rise to the formation of Cumulus (Cu) or Cumulonimbus (Cb) clouds and potentially trigger thunderstorms, provided there is an ample amount of water vapor present. Strong winds combined with moist air can induce convective instability, leading to the development of Cumulonimbus clouds and thunderstorms.

In regions characterized by rugged topography, this uplifting process can become quite vigorous, resulting in the generation of extensive cloud cover and vertical growth due to convective instability. Moreover, this can enhance the intensity of precipitation.

The orographic lift phenomenon amplifies the concentration and size of Supercooled Large Droplets (SLD), thus flying through orographic clouds increases the risk of icing. In stable atmospheric conditions, the freezing level is positioned lower, and the severity of icing is heightened both upwind and downwind of the mountainous range.