Bailu occurs at celestial longitude 165°, around September 7-9. Mornings cool enough that water vapor condenses on plants as visible white dew — the term's namesake.
Tradition: drinking white dew tea (白露茶), eating longan for kidney/blood. Climate: cool autumn truly begins in northern China; fruit ripening peaks.
The white in Bailu (白露 Bái Lù) is not a description of the dew. It comes from Five Phase correlation: autumn belongs to metal, sits in the west, and takes white as its colour. The Erya glossary names the four seasons Green Yang, Vermilion Brightness, White Store and Dark Blossom on exactly this logic, and autumn dew is white for the same reason. The Book of Songs opens its most famous autumn poem with reeds going grey and white dew turning to frost. Hearing the name as “dew that is white” misses the system behind it.
Bailu is a node, so the month pillar turns over: the branch moves from Shen to You (酉) and autumn reaches its middle third. You belongs to the small set of branches — with Zi and Mao — that hide a single stem and nothing else, in its case Xin metal. That makes the You month the cleanest stretch of metal in the year. The practical consequence is real: Shen-month metal still drags Ren water and Wu earth along with it, while You has no such cushion, and the relation between day master and useful god tends to be more direct and more cutting.
Several standing relations cluster around You. Xin takes You as its prosperity branch and Geng takes it as the blade; You is the centre of the Si–You–Chou metal trine; Chen and You form a six-harmony pair traditionally said to produce metal; and Mao and You clash, the clearest metal-against-wood opposition among the four cardinal branches. In a chart born after Bailu, further Shen, Xu, Si or Chou can consolidate the metal into a single mass — at which point schools differ on whether to drain it, restrain it, or follow it.
Treating Bailu as a temperature threshold is one recurring misreading; dew depends on radiative cooling and humidity at the surface and shows up on clear, still nights, while the term records a long-run average and not any single night's conditions. The other takes Bailu and Hanlu for the same thing in different degrees. In chart terms they are not: Bailu opens You and Hanlu opens Xu, and the hidden stems of the two months, along with everything that follows from them, have little in common.
Old almanac dates for Bailu often fail to line up with modern tables, and the reason is a change of method. Before the Qing the calendar used mean qi, dividing the length of the tropical year into twenty-four equal spans of time. From the mid-seventeenth century it used true qi, dividing the ecliptic into arcs of fifteen degrees instead. Since the earth's orbital speed is not uniform, the two can place the same term a day or more apart. A date taken from an older almanac needs checking against the method behind it before being compared with a modern one.
All three of Bailu's pentads concern birds: the wild geese arrive from the north, the swallows return south, and the flocks begin storing food. Marking a term by bird movement is characteristic of the seventy-two pentad scheme, and it also reveals where the observations were made — the middle Yellow River. Carried to Guangdong or to the northeast, the same phases simply do not fall at the same point in the year.
Dew has no colour. The white comes from Five Phase correlation, in which autumn belongs to metal, occupies the west, and is assigned the colour white; autumn dew is therefore white dew. The Erya glossary names the seasons on the same principle, calling autumn the White Store. Once that logic is clear, the many autumn expressions built on white stop looking like descriptions of appearance.
Yes. Bailu is a node, and at the moment it arrives the month branch moves from Shen to You. You conceals only Xin metal, with no secondary stems at all, which makes it the cleanest metal month of the year. Shen by contrast carries Ren water and Wu earth as well, so the two autumn months are handled quite differently despite belonging to the same season.
The difference goes well past cooler dew. Bailu falls at 165° and opens the You month, which hides only Xin metal. Hanlu falls at 195° and opens the Xu month, which hides Wu earth, Xin metal and Ding fire and serves as the storehouse of fire. A month separates them, the hidden stems differ completely, and so does the way each is handled in a reading.
Usually neither — the methods differ. Calendars before the Qing divided the year into twenty-four equal spans of time; later ones divide the ecliptic into equal arcs of fifteen degrees. Because the earth moves faster near perihelion and slower near aphelion, the two schemes can place the same term a day or two apart. Check which method an old almanac used before comparing its dates with a present-day table.
No. A prospering month branch describes the environment, not the whole chart. Whether metal is genuinely strong depends on the day master's own element, on the other seven characters, on whether metal surfaces in the stems and finds a root, and on whether fire restrains it or water drains it. The traditional method starts from the month command and then weighs the entire chart; judging elemental strength from the birth term alone skips the actual work.