When Does the 2018 Sanfu Period Start? With a Sanfu Period Timetable
The Sanfu period is the hottest stretch of the year, and also a good opportunity to treat winter ailments in summer. So when does the 2018 Sanfu period start? Let's take a look together at the 2018 Sanfu period timetable below!
When Does the 2018 Sanfu Period Start
The 2018 Sanfu period starts on July 17, 2018.
2018 Sanfu period dates: 40 days in total
July 17, 2018——July 26, 2018 is the first fu, 10 days
July 27, 2018——August 15, 2018 is the middle fu, 20 days
August 16, 2018——August 25, 2018 is the final fu, 10 days
The Sanfu period is calculated according to the lunar calendar, falling roughly between mid-to-late July and early August on the Gregorian calendar. The date of entering fu is not fixed each year, and the length of the middle fu also differs, so it needs to be calculated by consulting the almanac. Simply put, the four-character saying “third geng after the summer solstice” can indicate the date of entering fu, that is, counting from the 3rd “geng” day after the summer solstice: the first fu is 10 days, the middle fu is 10 or 20 days, and the final fu is 10 days.
Starting from the summer solstice, according to the arrangement of the heavenly stems and earthly branches for reckoning days, the 3rd geng day is the first fu, the 4th geng day is the middle fu, and the 1st geng day after the start of autumn is the final fu. When 4 geng days occur between the summer solstice and the start of autumn, the middle fu is 10 days; when 5 geng days occur, it is 20 days. From this it follows that how early or late the geng day falls will affect the length of the middle fu, which is why in some years the fu period is 30 days and in others it is 40 days.
Calculated in this way, the 2018 Sanfu period totals 40 days.
Why the Sanfu Period Forms
After entering fu, surface humidity increases; each day more heat is absorbed and less is released, and heat accumulates in the surface layer, so it gets hotter day by day. By the time the Sanfu period arrives, the accumulated heat on the ground reaches its peak, and the weather is at its hottest.
In addition, there is more rain in summer and the air humidity is high. The heat capacity of water is much greater than that of dry air, which is also an important reason for the muggy weather. In July and August, the subtropical high strengthens; under its control, the descending airflow inside the high makes the weather clear with few clouds, which favors sunlight and increases ground radiation warming, making the weather even hotter.
Which Fu Is Hottest During the Sanfu Period
The hottest stage of the Sanfu period: the middle fu
1. When it comes to which fu is hottest during the Sanfu period, one must mention the folk saying “cold in the sanjiu, hot in the middle fu”, meaning that the hottest days of the year belong to the “Sanfu”, and among the “Sanfu”, the “middle fu” is the hottest. After the final fu, the weather gradually becomes cooler.
2. First, after entering fu, surface humidity increases; each day the ground absorbs more heat and releases less, and heat accumulates in the surface layer, so it gets hotter day by day. Upon entering the middle fu, the accumulated heat on the ground reaches its highest value, and the weather is at its hottest.
3. In addition, there is more rain in summer and the air humidity is high. The heat capacity of water is much greater than that of dry air, which is also an important reason for the muggy weather of the Sanfu period.
4. In July and August, the subtropical high strengthens; under its control, the descending airflow inside the high makes the weather clear with few clouds, which favors sunlight and increases ground radiation warming, making the weather even hotter.
5. After entering the final fu, the weather gradually becomes cooler; mornings and evenings are relatively cool, while midday is still rather hot, and it varies from region to region. Because the final fu comes after the start of autumn, even during what is commonly called the “autumn tiger”, it is hot during the day but still cool in the mornings and evenings.
How the Dates of the Sanfu Are Determined
The first fu, according to the Chinese calendar system, is the true beginning of the hot season. People often say: hot in the Sanfu, cold in the Sanjiu. The Sanfu period is the season with the highest temperatures and greatest humidity of the year, divided into the first fu, middle fu, and final fu, among which the first fu and final fu are both fixed at 10 days, while the middle fu is 10 days in some years and 20 days in others.
The start of the fu period is called entering fu or crossing into fu, and the end of the fu period is called leaving fu. The number of days in the middle fu depends on how early or late fu begins; generally, if fu begins before July 28, the middle fu is 20 days, and if fu begins on July 29, the middle fu is 10 days.