Why do lips become dry during winter?

Question: Why do lips become dry during winter?
- Keywords:
  dry,
  face,
  human body,
  lip,
  seasonal,
  skin,
  weather,
  winter
Asked by alysha to Hitesh, Hywel, Mae, Nik, Tiffany on 13 Jun 2012.
- Tiffany Taylor answered on 13 Jun 2012:
  
  Because the air is very dry in the winter. Warm air allows water to evaporate and be held in the air (what we call humidity). When it is cold there is no evaporation and so the air is dry. This causes your lips to dry out and become chapped.

Question: Why do lips become dry during winter?