air_potential_temperature / (K)     (model_level_number: 70; grid_latitude: 100; grid_longitude: 100)
     Dimension coordinates:
          model_level_number                           x                  -                    -
          grid_latitude                                -                  x                    -
          grid_longitude                               -                  -                    x
     Auxiliary coordinates:
          level_height                                 x                  -                    -
          sigma                                        x                  -                    -
          surface_altitude                             -                  x                    x
     Derived coordinates:
          altitude                                     x                  x                    x
     Scalar coordinates:
          forecast_period: 0.0 hours
          time: 2009-09-09 17:10:00
     Attributes:
          source: Iris test case