Compare the difference of noise level measurement between a sunny day and a cloudy day. Which set of data is more reliable?

The temperature of the environment plays an important to differentiate the noise level between sunny and a cloudy day. In the sunny day air have high temperature due to sun and temperature of decreases when altitude increases. Due to this temperature difference the sound waves refract upward or we can say that away from the earth and causes the lower noise level. ON the other hand in cloudy day the temperature of air is low due to this the temperature of earth is also low. Due to this sound wave return back in to ground and cause the high noise level.

The wind will also alter the direction of sound by the mechanism of refraction. When wind is flowing along the sound propagation the heard sound will be loud on the other hand when flowing apposite to the propagation of sound wave then heard sound level will be low.

So among these two direction of wind can significantly impact the direction of flow of sound.