Yesterday was the 4th of July, so I went to go see the fireworks with some friends. That particular day was scolding hot. We laid on a miniscule square blanket on a warm cement bridge, bathing in sweat as we waited for the sun to go down. To make matters worse, it had rained recently and the air was very humid and sticky. It was all worth it to experience people screaming “America” and other patriotic screams while watching bomb-like explosions in the sky.
When people talk about humidity they are most likely referring to relative humidity. This basically refers to how “wet” the air feels. Low humidity can lead to dry skin, itchiness and thirstiness while high humidity will make hot temperatures feel hotter and cold temperatures to feel colder. It makes mildew, impacts electric circuits, microorganisms and fungi. Luckily, there is a way to gauge humidity so we know what to expect when leaving the house.
The first known humidity gauge was Leonardo’s hydrometer. Leonardo da Vinci basically just weighted a ball of wool. He noticed the weight changed depending on the moisture level of the air. As you can imagine, this was not a very effective design. It took 300 years before someone improved upon Leonardo’s gauge. About 200 years ago Horace Benedict de Saussure (that’s some name) noticed that hair changed lengths depending on the humidity level. During high humidity the hair would be longer than when there is little humidity.
Today, a psychrometer is used to measure humidity. It consists of two thermometers in tandem. A thermometer is basically a temperature gauge. It’s important to measure humidity levels for climate control in buildings. You want humidity to be right in the middle. At high temperatures, low humidity speeds up the evaporation of water and can dry the skin, furniture and cause paint to fracture. High humidity can cause condensation on surfaces, leading to decay and deterioration.