The video discusses a phenomenon that most people have commonly seen. Mist forms on any cold, smooth surface like the outside of a glass of ice water or the outside of a car's windshield in cold weather. If there is enough mist, it coalesces into drops and runs down the surface, Dew drops are formed on leaves by the same method but they only form overnight when the lowest temperature of the day is achieved. When the temperature is low enough, the water vapour in air condenses on cool surfaces like blades of grass and leaves to form dew drops.