Adhika masa and Kshaya masa
This article is regarding the concept of Adhikamasa and Kshayamasa (intercalary months) used in some luni-solar calendars in India. Luni-solar calendars are in vogue since lunar months determine the high and low tides while the solar year determines the seasons. But the use of luni-solar calendars create a unique problem. Since the lunar year (12 lunar months) lags behind the solar year (~365.25 days), this creates a need to keep the lunar year and the solar year in synchrony. Hence the need to use Adhika masa (extra month) and Kshaya masa (removed month)! The reason for their asynchrony is explained next.