As part of a discussion about the Mishna which described in which direction of the city may/may not one set up a tannery due to the bad smell and the direction that the winds travel, the Gemara discusses the strengths of each of the winds (winds from each of the four directions). A braita attempts to explain why we only see the sun during the day and also why summer days and winter days have different amounts of sunlight/daytime hours. One must distance a tree from a neighbor's pit as the roots will damage the pit. Details of this law are discussed.