What causes a section of an orchid's leaf tip to dry out?

Orchids like moisture, ventilation and air permeability. It is best to water with rainwater; in winter, water at noon, and do not water from the center of the leaves. Repot every two years, preferably using nutrient soil, and the soil should drain easily. Sunlight must not be direct, especially in summer. Sterilize every spring. When flower buds are forming, water as little as possible; in a ventilated spot, water once a week. Three parts management, seven parts watering.