Correct Option
The correct option is (c).
Explanation
The fundamental atmospheric processes involving the vertical distribution of temperature, the phase change of water (condensation), and the mechanism of precipitation within the troposphere.
Statement-wise Analysis
- Statement 1 is Correct: As an air parcel rises from the surface, it encounters lower atmospheric pressure, causing it to expand. This expansion requires energy, which is drawn from the internal heat of the air, resulting in a decrease in temperature. This process is known as adiabatic cooling. Additionally, under normal conditions in the troposphere, temperature decreases with an increase in altitude at an average rate of 6.5°C per kilometer (Normal Lapse Rate).
- Statement 2 is Incorrect: The capacity of air to hold water vapour is directly related to its temperature; warmer air can hold more moisture than cooler air. As rising air cools, its capacity to hold water vapour decreases. Once the air cools to its dew point, it becomes saturated, and excess water vapour transforms into liquid water droplets or ice crystals. Thus, cooling at heights causes condensation rather than preventing it.
- Statement 3 is Correct: Clouds are composed of microscopic water droplets or ice crystals suspended by upward air currents (updrafts). Through processes such as collision and coalescence, these droplets merge to form larger, heavier drops. When the weight of these drops exceeds the force of the supporting updrafts, they fall to the ground due to gravity as rain.
Key Takeaway: Rising air cools via expansion, leading to saturation and condensation; precipitation occurs when condensed droplets grow large enough for gravity to overcome atmospheric updrafts.