Vernal Equinox
On the vernal equinox, the sun is almost directly on the equator of the earth, and the length of day and night is almost equal in all parts of the world. The seasons are reversed in the northern and southern hemispheres, the northern hemisphere is the vernal equinox, and the southern hemisphere is the autumnal equinox.
At the vernal equinox, the sun is directly on the equator, and theoretically speaking, the length of day and night is equal across the globe. After the vernal equinox, the point of direct sunlight continues to move northward, the days in the northern hemisphere get longer and the nights get shorter, and the nights in the southern hemisphere get longer and the days get shorter.
At the vernal equinox, the global phenomenon of infinite day and polar night. After the vernal equinox, the polar day begins near the North Pole, and the range gradually increases; the polar day ends near the South Pole, and the polar night begins, and the range gradually increases.
