Let's carefully analyze the concept of humidity to understand the correct answer to the given question.
Relative humidity is a measure of how much water vapor is present in the air compared to the maximum amount of water vapor the air can hold at a given temperature. It is expressed as a percentage.
1. Relative Humidity of 90%:
When a weather report says there is 90% humidity, it indicates that the air contains 90% of the maximum amount of water vapor it can hold at that particular temperature.
Now, we can examine the options given in the question to see which one aligns with this explanation.
- Option a: "The air has 10% as much water vapor as it could hold at that temperature."
- This is incorrect because it refers to 10% humidity, not 90%.
- Option b: "The air has 90% as much water vapor as it could hold at that temperature."
- This statement aligns with our understanding of relative humidity. If the humidity is 90%, it means the air holds 90% of the maximum possible water vapor.
- Option c: "The air is 90% water vapor."
- This is incorrect. If the air were 90% water vapor, it would mean that water vapor constitutes 90% of the air's composition, which is not how relative humidity is measured.
- Option d: "The air is 10% water vapor."
- This is also incorrect. Similar to option a, this would refer to a different percentage of humidity.
Based on the above analysis, the correct answer is:
Option b: The air has 90% as much water vapor as it could hold at that temperature.
