1. Time in Sun 2. Angle of Sun 3. Sufficient Cholesterol Just 13 min and The time of day is critical.. the sun must be above 50' above horizon for UVB to pen

1. Time in Sun 2. Angle of Sun 3. Sufficient Cholesterol Just 13 min and The time of day is critical.. the sun must be above 50' above horizon for UVB to penetrate the atmosphere to reach the skin. When your skin is exposed to sunlight, it makes vitamin D from cholesterol https://theralightinc.com/best-time-to-get-vitamin-d-from-sunlight/ https://theralightinc.com/best-time-to-get-vitamin-d-from-su... https://www.healthline.com/nutrition/vitamin-d-from-sun#time-of-day https://www.healthline.com/nutrition/vitamin-d-from-sun#time...