What are forms of condensation? Describe the process of dew and frost formation.
Condensation is the transformation of water vapour into water caused by the loss of heat. When moist air is cooled, the excess water vapour condenses. The main forms of condensation are dew, frost, fog, and clouds, which are classified based on temperature and location.
Dew is formed when moisture is deposited in the form of water droplets on cooler surfaces of solid objects such as stones, grass blades, and plant leaves. For dew to form, it is necessary that the dew point is above the freezing point. The ideal conditions for its formation are a clear sky, calm air, high relative humidity, and cold and long nights.
Frost forms on cold surfaces when condensation takes place below the freezing point (0°C). In this case, the dew point is at or below the freezing point. The excess moisture is deposited in the form of minute ice crystals instead of water droplets.
The ideal conditions for frost are similar to those for dew, except that the air temperature must be at or below the freezing point. While dew appears as liquid water on objects, frost appears as a crystalline deposit.
Explanation
The answer draws directly from the textbook definitions provided in the context. It identifies the forms of condensation (dew, frost, fog, clouds) and explains the specific processes for dew and frost. For dew, it highlights the requirement of the dew point being above freezing and lists the ideal conditions (clear sky, calm air, etc.). For frost, it distinguishes the process by the temperature being at or below freezing, resulting in ice crystals rather than water droplets.