Some dew drops on a leaf.
Dew is a thin film of water that has condensed on the surface of objects near the ground in the morning or evening. These objects cool in the night. When they cool, the thin layer of air around them cools too. This makes some water vapor condense on the object. The condensation happens because the air is able to hold less water when it is cooled. The temperature at which condensation begins is called the dew point. If the dew point temperature becomes lower than 32 °F (0 °C), the dew turns into frost. Most people agree that the water in the dew comes from the atmosphere. However, some studies suggest that it also comes up through the soil and then condenses on the ground. This happens, though, only when conditions are right.
