Ever notice that when it’s humid you have a Bad Hair Day? Hair increases its length when humidity increases. So curly hair frizzes and straight hair goes limp. From dry to humid, hair length can change by 3 percent.
In this activity, we’ll hook up a hair to a lever system and create a hair hygrometer to measure changes in humidity. Invented in 1783, the hair hygrometer was so reliable that it was not replaced by an electrical instrument until the 1960s.