What happens to the daylight period in the northern hemisphere after June 21 and why?

After June 21, the daylight period in the northern hemisphere begins to shorten as the Earth continues its orbit around the Sun. This date marks the summer solstice, when the northern hemisphere is tilted closest to the Sun, resulting in the longest day of the year. Following this, as the tilt decreases relative to the Sun, the days gradually become shorter until the winter solstice around December 21. This seasonal change occurs due to the axial tilt of the Earth and its elliptical orbit around the Sun.