(a) Condensation is the reverse process of evaporation. In condensation, water vapour in the atmosphere get converted into water droplets or ice. Condensation takes place when water vapour is added to saturated air or when the temperature falls below the temperature at which air become saturated.
(b) The atmospheric conditions that favour condensation are :
1. There should be a high amount of water vapour present in atmosphere.
2. Minuscule particles of dust, salt and even smoke act as condensation nuclei.
3. The temperature of air must be below dew point temperature so as to encourage condensation.
(c) Forms of condensation : Following are the forms of the
1. condensation : Dew, frost, fog, mist, white frost and clouds. The clouds are formed when the temperature falls down below dew points, while dew, fog and clouds are formed when the temperature remains higher than the freezing point.
2. Clouds : Clouds are formed when minute droplets of water vapour condense on a nuclei and remain suspended in air.
3. Dew : When water vapour condenses on the surface, it forms tiny droplets of water called dew. Dew commonly occurs during winter on account of cooling of air below dew point.
4. Frost : In very low temperature, when condensation occurs at zero metre or ground level, water vapour freezes into minute crystals of rice on objects near the ground such as blades of grass, leaves and tiny rock particles. Frost is harmful to plants.
5. Fog and Mist : Fog and Mist are two related terms. Droplets of water suspended in the atmosphere close to the surface of the earth are termed as fog. On long winter nights, the ground cools more rapidly than the air above. Such cooling reduces temperature at the surface to below dew point. Water vapour at lower levels get condensed around minute solid particles to form fog.
