The Jewish Leap Year

Rabbi, I have a Question concerning the "parameter" of The 13th Month, and the "institution" of this mandate within the frame work of Torah (Jewish Thought). How is this mandate, the process administered within the frame work of Torah. Please, help me to understand the nineteenth year cycle of The Jewish Year. Thanks Rabbi. Dawid

The Jewish "leap year", which occurs seven times in a 19-year cycle, has 13 months instead of the regular year's 12. This is so that the lunar-based Jewish year should remain aligned with the solar seasons (12 lunar months make up a total of 354 days — slightly more than 11 days short of the 365.25 day solar cycle). The added month is called "Adar I" and is inserted before the month of Adar (termed "Adar II" in leap years) (copied this from a Chabad site). This is done in years when the month of Nissan would otherwise not fall during the spring-season (in Israel).