Why street trees are planted in a straight line in downtown Seoul

There are trees planted to block the wind, but they actually create a forest that invites it. Instead of planting them in a wide cluster, they are planted in a long line to create a pathway for the cold air generated in the mountains to flow into the city. This air, descending the hillsides overnight, is weak and gets blocked even by a single building. Therefore, they calculate the actual paths of wind flow and plant the trees only in pre-existing openings, like along riverbanks.