Skin discoloration can be due to changes in melanin. Melanin is a skin pigment that gives color to the skin. Changes in melanin can also cause skin to be patchy. Treatment for skin discoloration includes using topical treatments.
Winglets increase an aircraft's operating efficiency by reducing what is called induced drag at the tips of the wings. An aircraft's wing is shaped to generate negative pressure on the upper surface and positive pressure on the lower surface as the aircraft moves forward.
On the leading edge of the wing, there are leading edge slats. They are the orange shapes. Slats function in a very similar way to flaps. They extend when the plane is in flight and the nose is tilted at a steep angle up or down.