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Core Viewpoint - The article discusses the traditional Chinese lunar calendar, its structure, and the phenomenon of leap months, emphasizing that leap months are a normal occurrence in the calendar system and not related to climate anomalies [1][10]. Group 1: Lunar Calendar Structure - The lunar calendar is based on the moon's orbit around the Earth and the Earth's orbit around the sun, making it a lunisolar calendar [1]. - A lunar month is determined by the lunar cycle, averaging 29.53 days, leading to a lunar year of approximately 354 or 355 days, which is about 11 days shorter than a solar year [5]. - To align the lunar calendar with the seasons, ancient astronomers implemented a leap month system, adding 7 leap months in a 19-year cycle [6]. Group 2: Leap Month Mechanism - The leap month is determined based on the presence of solar terms, which divide the Earth's orbit into 24 segments, ensuring that each lunar month contains a solar term [6]. - If a lunar month lacks a solar term, it is designated as a leap month, with the current example being "leap June" in 2023, which has 29 days [7]. Group 3: Historical Context and Climate Relation - Leap June occurrences are not rare, with six instances recorded in the current century, including years like 2017 and 2025 [10]. - Recent extreme heat has been mistakenly linked to the leap month phenomenon, but experts clarify that leap months are a standard calendrical occurrence and do not indicate climate anomalies [10].