When the relative humidity in the garden is low, your resin production will increase. This is a natural response cannabis has to dry air, an attempt to protect itself from hot, dry conditions. Marijuana resin actually has one of the highest UV-resistance ratings in the plant kingdom. The resin reflects light, preventing the buds from getting sunburn. (This is also why it's so easy for helicopters to spot marijuana from the sky; it glows when seen through UV-sensitive equipment.)