summer solstice
夏至の日は一年で最も昼が長い。
The day of the summer solstice has the longest daylight of the year.
北欧では夏至を盛大に祝う風習がある。
In Northern Europe, there is a tradition of celebrating the summer solstice grandly.
夏至を過ぎると少しずつ日が短くなる。
After the summer solstice, the days gradually grow shorter.