Final answer:
The troposphere is the lowest layer of the atmosphere, while the stratosphere is the layer above it. The temperature in the troposphere decreases with increasing altitude, while in the stratosphere it increases. Aeroplanes fly best in the troposphere due to its stable atmospheric conditions.
Step-by-step explanation:
The troposphere is the lowest layer of the atmosphere, extending from the Earth's surface to an altitude of about 11-13 km. The temperature in the troposphere decreases steadily with increasing altitude.
The stratosphere is the layer above the troposphere and extends from about 11-13 km to 50 km above the surface. In the stratosphere, the temperature increases with increasing altitude due to the absorption of UV radiation by ozone.
Aeroplanes fly best in the troposphere because it is where most weather occurs and it has more stable atmospheric conditions compared to the stratosphere.