There is a leap 2nd lunar month (intercalary Month), in the Chinese Lunar Calendar year 2004. The following explanation can help you to know why. There are three basic rules for the Chinese Calendar.
Please read the Essence of the Chinese Calendar for detail about Solar Center Point.
The following is the listing of dates and times about new moon days and the Solar Center points. A lunar month not containing a Center Point is a Leap month.
2004 China Civil Calendar
|Month Name||New Moon Date/Time||Zodiac Date/Time||Note|
|1st Lunar Month||01-22 05:05||Chinese New Year Day|
|02-04 19:56||Start of Spring (Tiger Month)|
|02-19 15:50||Rain Water (Pisces) - Center Point|
|2nd Lunar Month||02-20 17:18|
|03-05 13:56||Excited Insects (Rabbit month)|
|03-20 14:48||Vernal Equinox (Aries) - Center Point|
|Leap 2nd Month||03-21 06:41||No Center point|
|04-04 18:43||Clear and Bright (Dragon Month)|
|3rd Lunar Month||04-19 21:21||04-20 01:50||Grain Rains (Cancer) - Center Point|
|05-05 12:02||Start of Summer (Snake Month)|
There is no Solar Center Point in the lunar month from 3-21-04 to 4-19-04. Therefore this lunar month is assigned as a leap month. The name of the lunar month repeats the previous month. It called leap 2nd lunar month.
The assignment of the Leap Lunar Months is very complicate. For more information about the Chinese Lunar Calendar and Leap Month, please read the Essence of the Chinese Calendar.
All the detail Chinese Lunar Calendar conversion information are available at Chinese Lunar Calendar and High-Precision Astronomical Data CD.