Detailed Explanation:

Answer: Option 1 — 1 only

Statement 1 is correct because water vapour concentration decreases with altitude as colder air at higher elevations has a reduced capacity to hold moisture. Statement 2 is incorrect because water vapour percentage is maximum near the equator (due to higher temperatures and evaporation) and minimum at the poles, not the other way around.

✅ Statement 1 – Correct: Water vapour is a gas that decreases with altitude because temperature drops at higher elevations, reducing the air's moisture-holding capacity.
❌ Statement 2 – Incorrect: Water vapour percentage is maximum at the equator (warm, high evaporation) and minimum at the poles (cold, low evaporation).

📝 Short Notes: Atmospheric Water Vapour

• Nature: Water vapour is an invisible gas and the most variable component of the atmosphere, ranging from 0% to 4% by volume.
• Vertical Distribution: Concentration decreases rapidly with altitude; about 50% of atmospheric water vapour is found below 2 km, and 90% below 6 km altitude.
• Horizontal Distribution: Maximum concentration occurs in the equatorial region (hot, high evaporation) and decreases towards the poles (cold, low evaporation).
• Temperature Dependency: Warm air can hold more moisture than cold air; at 30°C, air can hold about 4 times more water vapour than at 0°C.
• Role in Weather: Water vapour is crucial for cloud formation, precipitation, and latent heat transfer, which drives weather systems and storms.
• Greenhouse Gas: Water vapour is the most abundant greenhouse gas, contributing significantly to the natural greenhouse effect and Earth's temperature regulation.
• Sources: Primarily from evaporation of ocean water (oceans cover 71% of Earth's surface), followed by lakes, rivers, soil moisture, and transpiration from plants.