Sounds like you've had a problem getting your do just right. People say big hair a lot. Big hair usually means that someone's hairdo is big and puffy like Dolly Parton or Tina Turner. But the big hair I'm talking about is when places in your hairs actually get bigger and fatter.
Humidity is the amount of water there is floating in the air as a gas - water vapor.
It can actually changes the shape of hairs and can frizz out your coiffure. If you were to look at hair through a microscope, you'd see all these little scales. You can even feel them by stroking your hair. From your head outward, it's smooth. But the other way you can feel the edges of these scales.