People often say that areas like Arizona and Nevada don’t feel as hot as the temperature would indicate because it is a dry heat. But what does that mean?
When people describe the air, heat, or temperature as wet or dry, they are talking about the humidity reading in the air. The level of humidity in the air is the amount of water vapor circulating.
The more humid, the more ‘wet’ the weather feels – and the more intensely humans feel the temperature. A very humid, hot day feels like a scorcher because the water in the air makes it harder for our sweat to evaporate, the way the human body cools itself.
A wet, cool day feels colder because your skin is carrying that extra moisture it gets from the air, which then evaporates, cooling you down.
When you discuss humidity in terms of the weather, you’re discussing how to measure relative humidity, not absolute or specific humidity. These terms have importance in other fields of science and technology, but they aren’t relevant in the weather.
The Tools for Measuring Humidity
Many people don’t know how to actually gauge humidity in the air. The device to measure humidity is called a hygrometer, and it can be used for both indoor and outdoor humidity. It looks very similar to a thermometer in most cases and is often packaged with one.
There are two main types of hygrometers: analog readers, and digital readers. An analog hygrometer uses water-sensitive materials, combined with a spring inside, to gauge humidity in the air and move a dial.
The wetter the air is, the more the dial moves, increasing the reading. These are commonly found on outdoor or water-resistant thermometers and have been used for years. Another less common name is ‘wet-bulb thermometer.
Digital hygrometers are a little more high tech, using sensors to measure for humidity in the air, either indoors or outdoors. They are normally packaged as a device that does a lot, like tell you the weather, the temperature outside, and more.
Digital hygrometers are nice because they can also store and read to you the historical data for years past, what data trends predict for the future and more.
The benefits of knowing how to measure humidity include being able to prepare for your day and staying cool or warm, despite which climate you’re located in.