Most Natural Smog:The thick cloud is a man-made product; the areas below in the valleys are used for planting pine trees, so when new lots are cleared in preparation for planting in the spring, the cut trees are burnt off.

View of a valley covered with smoke, from Peine, Lircay, Vilches, Chile.

Most Natural Smog

The thick cloud is a man-made product; the areas below in the valleys are used for planting pine trees, so when new lots are cleared in preparation for planting in the spring, the cut trees are burnt off.