# Chapter 17 - Reading Check Questions (Comprehension): 9

Humidity measures how much water vapor is in the air, and is measured in units such as $\frac{kg}{m^{3}}$. Relative humidity is the ratio of the amount of water vapor in the air to the largest possible amount of water vapor the air can hold at that temperature, and can be expressed as a percentage.

#### Work Step by Step

This is discussed on page 324.

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