Final answer:
Elevation affects temperature at night due to thinner air at higher altitudes leading to less heat retention, adiabatic cooling, less direct sunlight during the day, and variations in surface emissivity.
Step-by-step explanation:
Elevation affects temperature at night above the surface primarily because the atmosphere is thinner at higher altitudes, which means there is less insulation to retain heat during the night. Additionally, the law of adiabatic cooling states that as air rises, it expands due to lower pressure at higher altitudes, which causes it to cool. Therefore, temperatures tend to decrease with elevation, which is why mountain tops can be capped with snow even in tropical zones.
Moreover, the angle of the Sun's rays is less direct at higher elevations, resulting in less concentrated heat input during the day, which means there is less heat to lose at night. Finally, the concept of emissivity suggests that surfaces with different compositions, such as snow or cloud coverage at high altitudes, will emit radiation differently, influencing night-time temperatures.