JAMB Geography 2023 Paper

Concept:Air temperature in the troposphere decreases steadily with altitude at the environmental lapse rate of about $6.5^\circ C$ per $1000$ metres.Explanation:For every $1000$ metres of ascent, the temperature drops by $6.5^\circ C$.The aeroplane climbs $4000$ metres, so the total temperature decrease is:$$6.5^\circ C \times \frac{4000}{1000} = 6.5^\circ C \times 4 = 26^\circ C$$Subtract this drop from the ground surface temperature:$$40^\circ C - 26^\circ C = 14^\circ C$$Hence, the surrounding temperature at the aeroplane's altitude is $14^\circ C$.Answer:A. $14^\circ C$