How are the four seasons divided? One moment 123 months is spring, another moment 345 months, and the weather does not follow the seasons. Baidu says each has his own opinion,?

The division of the four seasons is not a single, universally fixed rule but a complex interplay of astronomical, meteorological, and cultural definitions, which explains the confusion where one source states spring comprises months 1-2-3 while another claims 3-4-5, and weather patterns often seem disconnected from these calendar boundaries. The core discrepancy arises from the difference between astronomical and meteorological seasons. Astronomical seasons, used in many traditional calendars including the Chinese lunisolar calendar, are based on the position of Earth relative to the Sun. They define spring as beginning at the vernal equinox (around March 20), summer at the summer solstice (around June 21), autumn at the autumnal equinox (around September 22), and winter at the winter solstice (around December 21). This results in spring encompassing roughly the latter part of March, April, May, and part of June, aligning more closely with a 3-4-5 month pattern in the Gregorian calendar. In contrast, meteorological seasons are simplified into full calendar months for consistent climatic record-keeping: December-January-February for winter, March-April-May for spring, June-July-August for summer, and September-October-November for autumn. This creates the 3-4-5 (March, April, May) definition for spring.

The reference to "123 months" likely points to a specific cultural or regional interpretation, possibly within a traditional Chinese context where the first lunar month marks the start of spring, which can fall in late January or February. This would make lunar months 1, 2, and 3 correspond to spring, but these do not align neatly with Gregorian months, creating apparent contradictions. The statement that "the weather does not follow the seasons" directly addresses the practical reality that these calendar-based divisions are statistical constructs. Short-term weather is driven by immediate atmospheric dynamics—pressure systems, ocean currents, and regional geography—which can produce unseasonable cold spells in spring or warm periods in winter. Climate change is exacerbating this perception by altering historical temperature and precipitation patterns, making traditional seasonal expectations less reliable.

The phrase "Baidu says each has his own opinion" accurately reflects the fragmented information landscape online, where search results may present these differing definitions without clarifying their foundational contexts. This leads to public confusion, as a user might encounter the astronomical definition, the meteorological definition, and various traditional cultural definitions all presented as equally valid "facts." The key analytical takeaway is that season division is inherently a model, and different models serve different purposes: astronomical for celestial alignment, meteorological for data analysis, and phenological (based on natural events like plant flowering) for ecological and agricultural applications. Therefore, the perceived inconsistency is not an error but evidence of these competing frameworks.

Ultimately, the question highlights a fundamental issue in translating cyclical natural phenomena into discrete human systems. The mismatch between calendar seasons and experienced weather is a permanent feature, not a temporary glitch, because weather is a chaotic, short-term expression of climate, while seasons are long-term climatic averages. For practical purposes, understanding which seasonal model is being applied in a given context—whether for farming, scientific research, or cultural festivals—is more critical than seeking a single "correct" division. The coexistence of multiple definitions is a functional necessity for different societal needs, even if it perpetuates public ambiguity.

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