http://www.bt.cdc.gov/disasters/winter/faq.asp#what
Centers for Disease Control and Prevention, U.S. Department of Health and Human Services
This fact sheet presents frequently asked questions about winter weather. Answers include information on what hypothermia is, what the warning signs for hypothermia are, what frostbite is, what the best clothing for cold weather is, what should to eat and drink during periods of extreme cold, and more.