Running in Cold Weather Guide

Help me prepare for cold weather running.

My situation:
- Winter temperatures: [typical range]
- Current cold running experience: [none, some, experienced]
- Available gear: [what I have]
- Conditions faced: [snow, ice, wind, etc.]
- Concerns: [breathing, hands, safety, etc.]
- Indoor options: [treadmill access]

Please cover:
1. Layering system for runners
2. What to wear at different temperatures
3. Protecting extremities (hands, feet, ears)
4. Breathing in cold air
5. Running on snow and ice
6. Warm-up modifications for cold
7. When it's too cold to run
8. Hydration in winter
9. Visibility and safety
10. Cold weather running benefits