Why Does Hair Get Frizzy When It's Humid?

The video explains how humidity affects frizzy hair by interacting with keratin proteins. It details the role of chemical bonds, particularly hydrogen bonds, in changing hair shape. The unpredictability of water absorption leads to frizz. Historically, hair was used to measure humidity, as its length changes with moisture levels. This principle was applied in early hygrometers, demonstrating a practical application of frizz.

What historical significance does the hygrometer have in relation to measuring humidity?

How can one observe the changes in hair length due to humidity variations?