Although the actual atmospheric lapse rate varies, under normal atmospheric conditions the average atmospheric lapse rate results in a temperature decrease of 6.4C°/km (3.5F°/1,000 ft) of altitude above ground level. The measurable lapse rate is affected by the moisture content of the air (humidity).
The reason you have two sets of teeth probably comes down to size. A full set of permanent teeth would be too big to fit into a young child’s mouth. So milk teeth act as a bridge until the jaw is large enough to accommodate a full set of permanent teeth. The last teeth that emerge are your wisdom teeth.