Question

why is no dew formed a windy day or when the sky is cloudy?

Answer 1

because the dew has high tendency to be vaporise in those days and
the condition of fire may be happened

Answer 2

1. Dew forms when the air is just above the ground is cooled to its dew point.

2. The air above the ground gets cooled because the ground radiates the heat into the space.

3. If there are clouds overhead, then the clouds reflects the heat back to the ground, so it dkes not cool and no dew forms.

4. If the weather is windy, the air above the ground is mixed with the air higher up and the air above ground does not get cooled and no dew forms.

5. Hence, to form dew, a clear night mist be there.