assume that the average rate of temperature decrease in the troposphere
Although the actual atmospheric lapse rate varies, under normal atmospheric conditions the average atmospheric lapse rate results in a temperature decrease of 6.4 Â°C/km (3.5 Â°F or 1.95 Â°C/1,000 ft) of altitude above ground level. The measurable lapse rate is affected by the moisture content of the air (humidity).he decrease of an atmospheric variable with height, the variable being temperature unless otherwise specified. In the lower regions of the atmosphere (up to altitudes of approximately 12,000 metres (39,000 ft), temperature decreases with altitude at a fairly uniform rate.