Why is there no dew on a cloudy morning?

There is no dew in cloudy morning because the clouds are thick, and the temperature is not much different from the ground temperature, so it is impossible to condense water vapor to form dew.

Dew is water droplets that condense near the ground at night or early morning, become small ice crystals, and then melt on objects. Dew can only be formed under the weather conditions of stable atmosphere, small wind, clear sky and local cloudy ground heat loss. Because flowers, stones and other objects on the ground dissipate heat faster than air and the temperature is lower than air, when hot air comes into contact with these low-temperature objects, the air's ability to contain water vapor decreases and saturation will occur. Water vapor in the lower atmosphere adheres to grass, leaves, etc. and condenses into tiny water droplets, that is, dew.

If it is cloudy at night and there are clouds in the sky, the ground is like a quilt. After the heat hits the clouds, part of it turns back to the ground and the other part is absorbed by the clouds. This part of the heat absorbed by the clouds will slowly radiate to the ground in the later stage, and it is difficult for the ground temperature to drop and dew to appear. If the wind is strong at night, the wind makes the upper and lower air communicate, which increases the temperature of the air near the ground and makes the water vapor diffuse, so it is difficult to form dew.

So there is no dew on cloudy mornings.

If there is no dew in the morning, it means that the clouds have not dissipated and it will be cloudy during the day. But if it is cloudy during the day, the clouds will disperse at night, the ground temperature will drop rapidly at night, there will still be dew in the morning, and the weather will be fine during the day.