Seasonally changing landscape

Current landscape panoramas cannot reflect the changing appearance of the landscape during the year, with dry summer grass or snowy winter landscapes. Depending on location and solar longitude a new landscape "supertype" should automatically switch (when crossing a trigger longitude) or blend between different landscapes. The sub-landscapes may be any of the existing types whose location section is then ignored. Optimally, number of sub-landscapes is not restricted, but 4 seasons may do for a start.