With reference to the formation of clouds, consider the following statements: 1. Clouds are formed when water vapour in the air condenses at high altitudes. 2. At high altitudes, the air becomes too warm for condensation to occur. 3. Clouds are composed entirely of water vapour and not liquid droplets. Which of the statements given above is/are correct?

The correct option is (a). Explanation Clouds are visible aggregates of minute water droplets or ice crystals suspended in the atmosphere. Their formation is primarily driven by the cooling of air masses, which reduces the air's capacity to hold water vapour, leading to saturation and subsequent condensation. Statement-wise Analysis: - Statement 1 is Correct: Clouds form when warm, moist air rises. As the air ascends, it expands due to decreasing atmospheric pressure, leading to adiabatic cooling. When the air temperature drops to the dew point, water vapour condenses onto hygroscopic nuclei (such as dust or salt particles) to form clouds. - Statement 2 is Incorrect: In the troposphere, where most clouds form, temperature generally decreases with altitude (Normal Lapse Rate). The air becomes cooler at higher altitudes, which is the necessary condition for condensation to occur. If the air became warmer, it would hold more moisture as vapour rather than condensing it. - Statement 3 is Incorrect: Water vapour is an invisible gas. Clouds are visible because they are composed of liquid water droplets or ice crystals. If clouds were composed entirely of water vapour, they would be invisible to the naked eye. Key Takeaway: Clouds are formed by the condensation of water vapour into liquid droplets or ice crystals due to the cooling of air at higher altitudes. Water vapour itself is invisible; clouds are the visible result of its phase change.

With reference to the formation… - NCERT Class 6 Environment & Ecology MCQ

NCERT Class 6 Environment & Ecology — Chapter 1: Water

mcqmedium

With reference to the formation of clouds, consider the following statements:

Clouds are formed when water vapour in the air condenses at high altitudes.
At high altitudes, the air becomes too warm for condensation to occur.
Clouds are composed entirely of water vapour and not liquid droplets.

Which of the statements given above is/are correct?

NCERT textbook question

From NCERT Science - class 6 · Page 140

Options

A1 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

The correct option is (a).

Explanation

Clouds are visible aggregates of minute water droplets or ice crystals suspended in the atmosphere. Their formation is primarily driven by the cooling of air masses, which reduces the air's capacity to hold water vapour, leading to saturation and subsequent condensation.

Statement-wise Analysis:

Statement 1 is Correct: Clouds form when warm, moist air rises. As the air ascends, it expands due to decreasing atmospheric pressure, leading to adiabatic cooling. When the air temperature drops to the dew point, water vapour condenses onto hygroscopic nuclei (such as dust or salt particles) to form clouds.
Statement 2 is Incorrect: In the troposphere, where most clouds form, temperature generally decreases with altitude (Normal Lapse Rate). The air becomes cooler at higher altitudes, which is the necessary condition for condensation to occur. If the air became warmer, it would hold more moisture as vapour rather than condensing it.
Statement 3 is Incorrect: Water vapour is an invisible gas. Clouds are visible because they are composed of liquid water droplets or ice crystals. If clouds were composed entirely of water vapour, they would be invisible to the naked eye.

Key Takeaway:
Clouds are formed by the condensation of water vapour into liquid droplets or ice crystals due to the cooling of air at higher altitudes. Water vapour itself is invisible; clouds are the visible result of its phase change.

Your note

More from Chapter 1: Water

What happens to the water that falls on land as rain and snow? 1. Most of it ultimately flows back to the oceans. 2. None of the rainwater seeps into the ground. 3. It remains permanently on the land surface to form lakes. Select the correct answer using the code given below:

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How does rapid industrialization primarily affect freshwater availability?

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With reference to heavy rains and floods, consider the following statements: 1. Heavy rains can lead to a rise in the water level of rivers and lakes. 2. Floods are generally beneficial for the survival of soil-dwelling animals. 3. Animals living in water can get carried away to land areas during floods and die when water recedes. Which of the statements given above is/are correct?

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What causes the formation of water droplets on the outer surface of a container filled with ice-cold water?

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Which of the following factors contribute to the decreasing availability of usable water? 1. Rising population. 2. Industries consume a negligible amount of water compared to domestic use. 3. Food production requires no water resources. Select the correct answer using the code given below:

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