(a) Any county or city may adopt, effective not later than January 1, 1984, and may enforce an ordinance that regulates the construction of tall buildings or structures on protected mountain ridges by any person. The ordinance may provide for the issuance of permits to construct tall buildings on protected mountain ridges, the conditioning of such permits, and the denial of permits for such construction. Any ordinance adopted hereunder shall be based upon studies of the mountain ridges within the county, a statement of objectives to be sought by the ordinance, and plans for achieving these objectives. Any such county ordinance shall apply countywide except as otherwise provided in Article 2 of Chapter 160D of the General Statutes and any such city ordinance shall apply citywide, to construction of tall buildings on protected mountain ridges within the city or county, as the case may be. A city with a population of 50,000 or more may adopt, prior to January 1, 1986, an ordinance eliminating the requirement for an elevation of 3,000 feet, as permitted by G.S. 113A-206(6).