A high-resolution cloud model is used to explore in detail the generation of the morning glory, a low-level non-linear atmospheric internal wave observed on the southwestern side of Cape York Peninsula (Australia). The model is two-dimensional and non-hydrostatic, and simulates an east-west cross section of the southern part of Cape York Peninsula at a horizontal resolution of 200m. The model is initialised at sunrise with a 5m/s easterly flow and a sounding taken upstream from the peninsula.

The sea breezes that develop over Cape York Peninsula are highly asymmetric with the east-coast sea breeze being both deeper and warmer than the western counterpart. When the sea breezes meet, the east-coast sea breeze rides over that from the west coast and in the process produces a series of waves that propagate on the west-coast sea breeze. The model calculations show that when the phase speed of these waves matches the westward propagation speed of the east-coast sea breeze, the waves grow to large amplitude thus forming the morning glory. When the east-coast sea breeze propagates too fast relative to the waves, the waves do not amplify. The number of waves produced depends on the stability of the west-coast sea breeze and the strength of the east-coast sea breeze. These numerical experiments have for the first time explicitly modelled the generation of the morning glory through the interaction of two sea breezes.

The inclusion of orography representative of Cape York Peninsula does not change the overall result with a morning glory forming in much the same way as in the case without orography. The main difference is that the sea breezes meet earlier when orography is included. An isolated hill on the west coast is considered also with westward propagating waves of smaller amplitude being generated by the west-coast sea breeze alone. However, the amplitude of these waves is much smaller than the morning glory that results from the interaction of the east-coast and west-coast sea breezes.