air_potential_temperature / (K)     (grid_latitude: 100; grid_longitude: 100)
    Dimension coordinates:
        grid_latitude                             x                    -
        grid_longitude                            -                    x
    Auxiliary coordinates:
        surface_altitude                          x                    x
    Derived coordinates:
        altitude                                  x                    x
    Scalar coordinates:
        forecast_period             0.0 hours
        level_height                5.0 m, bound=(0.0, 13.333332) m
        model_level_number          1
        sigma                       0.9994238, bound=(1.0, 0.99846387)
        time                        2009-09-09 17:10:00
    Attributes:
        source                      'Iris test case'