Correct Option
The correct option is 2 only.
Explanation
Clouds are masses of minute water droplets or ice crystals formed by the condensation of water vapour in free air at considerable elevations. Because clouds are formed at some height over the surface of the earth, they take various shapes. According to their height, expanse, density, and transparency or opaqueness, clouds are grouped under four types: Cirrus, Cumulus, Stratus, and Nimbus.
Statement-wise Analysis
- Statement 1 is Incorrect. Clouds are formed by the condensation of water vapour in free air, not evaporation. Evaporation is the process by which water changes from a liquid to a gas or vapour. Condensation is the reverse process where water vapour becomes liquid. As the air rises, it cools, and the water vapour condenses around hygroscopic nuclei to form clouds.
- Statement 2 is Correct. Clouds are classified based on criteria such as height, expanse, density, and transparency. The four primary types are:
- Cirrus: High altitude, feathery.
- Cumulus: Cotton wool-like, flat base.
- Stratus: Layered, covering large portions of the sky.
- Nimbus: Black or dark gray, rain-bearing.
- Statement 3 is Incorrect. Cirrus clouds are formed at high altitudes (8,000 - 12,000 m). They are thin and detached clouds having a feathery appearance. They are always white in colour. It is the Nimbus clouds that are typically black or dark gray.
Key Takeaway
Key Takeaway: Clouds result from the condensation of water vapour, not evaporation. Cirrus clouds are high-altitude, white, feathery clouds composed of ice crystals, whereas Nimbus clouds are dark and associated with precipitation.