The name "Chong Yang" in Chinese actually means "double Yang," and while that might be reminiscent of Chris Farley's explanation of El Nino, the Yang in this case actually comes from the Chinese concept Yin and Yang. In a nutshell, Yin and Yang represent the positive and negative sides of everything. Yin is considered to be the negative side, while Yang was dubbed positive. This concept was applied to numbers: even numbers belong Yin, and odd ones to Yang. Since nine is an odd number, it belongs to Yang, and since this is a double nine: Double Yang. Also noteworthy, since nine is the largest odd number, putting two nines together symbolizes longevity. Often, there is a focus on the elderly during this celebration.
So how is Chong Yang celebrated? Well, legend has it that a man named Huan Jing was told about a terrible event that would happen on the ninth day of the ninth month, and that he had to rush home and take his family to the top of a mountain, spray dogwood on his bags, and drink chrysanthemum wine to escape their plight. Long story short, they climbed the mountain, sprayed their bags, and drank the wine. This is the tradition that continues today, and the fall weather is perfect for doing this. Many people head outdoors and either hike or climb in the country, and this is generally the last time in the year that people have a chance to do this before winter.