Some sights in the tea fields in Japan are strange. The green rows of tea trees are covered with fans stuck up on top of numerous posts and their metal spikes give contrast to the soft aspects of spring. What can they actually be for? Give a little breeze when the sun is too hot? Certainly not! The fans will fully play their part in the middle of winter. They will be switched on in order to give the atmosphere a stir and prevent the layers of cold air to stay above the trees. These layers of cold air could indeed damage the small trees or slow down their growth.