During the night in winters, the temperatures come down a lot. At lower temperatures the amount of saturated water vapour in air is less than that at higher temperatures.
So as the temperatures go lower, the water vapour precipitates in the form of small globules , mist and droplets. Very small dust particles also are present in air. They make the air and water particles in air as opaque. The water droplets accumulate and when they are heavy, fall on the grass, roads which we observe in the morning.
As the temperature rises in the morning, the water evaporates again back in to the air.