Stone heads with grim faces probably represented a god.

Rain God

Introducing from a legendary sketch by Miguel Covarrubias for investigating the source of the Mesoamerican rain gods Chac and Cocijo, and  Tlaloc to an Olmec "were-jaguar".  Karl Taube verifies Covarrubias's fundamental insight, which maintains that rain gods of the religions descended or seminally inspired by the Olmec ritual from an Olmec jaguar Rain God with intensely furrowed eyebrows, snarling down turned mouth,  and frequently slitted eyes possibly grieving tears of rain.

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer