Skin remains red after a bad sun burn because:
inflammation causes increased blood flow.
Explanation:
When our skin is exposed to sun rays , the epidermal layer starts getting damaged. The damage to the cell caused by sun rays triggers the melanin secretion. Increased secretion of melanin results in darkening of the exposed region .
However, the damage and inflammation to the skin increases blood flow to the skin, this causes reddening of the skin.
