What is the electric polarity of the earth?

Question

Is the ground negatively charged and the Air positively charged.

Answer 1

The earth is the zero-voltage reference level. In fact it is a sort of charge reservoir which can absorb charges.

Air gets charged due to static electricity due to friction in clouds(eg in thunder storms.) and sometimes it induce a temporary charge on earth and the discharge is seen as lightning.

Answer 2

I would say negative polarity.  (why they call it "ground.")