How does your skin react in the sun?
Generally speaking, people with fair skin produce less melanin which is the body's natural way of protecting itself from sun exposure. Certain skin types produce melanin at a greater rate during similar sun exposure, allowing the skin to appear darker, and thus also have better protection from the sun. Sunscreens are necessary however for all skin types.
How you tan in the sun can also depend on:
Time: the sun is at its strongest between 10am and 2pm so limit your exposure between these times.
Clouds: UV rays easily penetrate cloud cover so wear sunscreen whenever your skin is exposed.
Surfaces: water, sand, tiled pool decks, concrete and of course snow refract a higher amount of rays.
Season: during summer the angle of the sun is much more intense, meaning exposure to stronger rays than at other times.
Altitude: the Earth's atmosphere absorbs and refracts the stronger rays.
Latitude: the closer you get to the equator the more intense the UV rays become.
Age: young children and adults have more sensitive skin.