When does the beginning of spring mean?

The first half of February in the solar calendar and the first half of January in the lunar calendar are beginning of spring (the season of leap month is uncertain). Astronomy takes "vernal equinox" as the beginning of spring, while climatology takes the five-day average temperature as the unified standard to divide the seasons around. When the five-day average temperature rises to 10℃, winter ends and spring begins.

Beginning of spring is a solar term reflecting seasons and phenology, which means that the spring of everything's recovery has begun, the weather will gradually get warmer, and the vast land will present a vibrant scene. As the saying goes: "Spring hits five Kyubi no Youko, and spring hits six or nine heads." In other words, the days of beginning of spring are not in Kyubi no Youko, but in Liujiutou. After beginning of spring, the days became longer, the temperature rose slowly, the soil began to thaw from the lower layer, and the frozen soil became shallower.