On the vernal equinox, the sun crosses directly over the Earth's equator. Day and night are nearly equal in length (about 12 hours each). After this point, the Northern Hemisphere begins to tilt toward the sun, leading to longer days and warming temperatures.
In the Southern Hemisphere:
Seasons shape what we eat, how we work, where we travel, and even how cultures mark the year. But “when” seasons start depends on which definition you use — astronomical, meteorological, or cultural — and on where you are on Earth. This post explains each system, why they differ, and what those differences mean for weather, ecosystems, culture, and everyday life. when do the four seasons start and end