Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       Astra Plinius - celestial bodies
         Universe
           (Supercluster) Virgo-Hydra-Centaurus Supercluster
             (Supercluster) Virgo Supercluster
               (Cluster) Local Group
                 (Galaxy) Milky Way Galaxy veter.
                   (Spiral arm) Orion Arm
                     (Region) Local Bubble
                       Local Interstellar Cloud
                         (Planetary system) Solar System
                           (Planet-satellite system) Earth System
                             (Planet) Earth veter.
                               "spheres" (Earth)
                                 (Sphere) Atmosphere (Earth) - layer of air
                                   (Phenomenon) Meteors
                                     (Phenomenon) Hydrometeors
                                       (Phenomenon) Clouds
                                         1 Phenomenon High Clouds
                                         2 Phenomenon Middle Clouds
                                         3 Phenomenon convective clouds of great vertical extent
                                         4 Phenomenon Low Clouds