Hair care
Scalp hair grows, on average, at a rate of about 1.25 centimeters per month, and shampoos or vitamins have not been shown to noticeably change this rate. Hair growth rate also depends upon what phase in the cycle of hair growth one is actually in; there are three phases. The speed of hair growth varies based upon genetics, gender, age, hormones, and may be reduced by nutrient deficiency (i.e., anorexia, anemia, zinc deficiency) and hormonal fluctuations (i.e., menopause, polycystic ovaries, thyroid disease).
Hair ice
Hair ice forms on moist, rotting wood from broadleaf trees when temperatures are slightly under and the air is humid. Each of the smooth, silky hairs has a diameter of about and a length of up to . The hairs are brittle, but take the shape of curls and waves. They can maintain their shape for hours and sometimes days. This long lifetime indicates that something is preventing the small ice crystals from recrystallizing into larger ones, since recrystallization normally occurs very quickly at temperatures near .