More than 90 percent of the total atmospheric water-vapour is found upto the:

Question

Accepted Answer

The correct answer is Option 2: 5 km height.

Here's why:

*   **Why Option 2 (5 km height) is correct:** The vast majority of atmospheric water vapor is concentrated in the lower troposphere. Water vapor is heavier than dry air, and its concentration decreases rapidly with altitude. While the troposphere extends much higher (around 10-15 km), over 90% of the total atmospheric water vapor is found within the first 5 kilometers. This is because the primary sources of water vapor (evaporation from oceans, lakes, and rivers, and transpiration from plants) are at the Earth's surface. As you move higher, the air becomes colder, reducing its capacity to hold moisture, and the distance from the water sources increases.

*   **Why Option 1 (2 km height) is incorrect:** While a significant portion of water vapor is found in the first 2 km, it's not *more than 90 percent* of the total. A considerable amount of water vapor extends beyond this altitude, up to around 5 km. Therefore, 2 km is an underestimate.

*   **Why Option 3 (10 km height) is incorrect:** 10 km is near the top of the troposphere. While some water vapor exists at this altitude, the vast majority (over 90%) is concentrated much lower, within the first 5 km. The air at 10 km is significantly colder and drier, holding far less water vapor.

*   **Why Option 4 (15 km height) is incorrect:** 15 km is well into the upper troposphere or even the lower stratosphere in some locations. The amount of water vapor at this altitude is extremely low compared to the lower troposphere. The vast majority (over 90%) is found much lower, within the first 5 km.