Trivia: What does a hygrometer measure in a greenhouse?
Hours of sunlight
Inches of rain
Correct Answer: Humidity
So why is this answer correct? : Hygrometers measure the amount of water vapor in the air, also known as humidity. There are different types of hygrometers, but one of the most common is used in greenhouses to help maintain the appropriate humidity levels. Aside from greenhouses, these devices might be used to measure the humidity in industrial spaces, saunas, and even museums.