In the Arctic, white-outs occur during blizzards but also when there is too much light. It happens, as Barry Lopez explains in Arctic Dreams, "where light travelling in one direction at a certain angle has the same flux, or strength, as light travelling at any angle in any other direction". The two streams collide and cancel one another. "There are no shadows. Space has no depth. There is no horizon. The bottom of the world disappears. On foot, you stumble about in missed-stair-step fashion." Lopez says that to stumble focuses uson the "narrow impetuosity" of our human scales and grasp of order. "It is precisely because the regimes of light and time in the Arctic are so different that this landscape is able to expose in startling ways the complacency of our thoughts about land in general."