What solar terms? The Tropic of Cancer stands upright without shadow.

Standing on a day without shadow is the solar term from summer to solstice.

Standing on a pole without shadow is a natural sight, that is, objects standing upright on the ground have no shadow. At noon from the summer solstice, the sun shines directly on the tropic of cancer in an absolute (almost) direct shape, and there will be a short-term "instant" phenomenon in the tropic of cancer area. The phenomenon of "immediate effect" only appears in the area south of the Tropic of Cancer, and the sun shines vertically on the ground twice a year.

Cause of occurrence

From summer solstice, the sun shines almost directly on the Tropic of Cancer, which is the highest latitude that can be reached by direct sunlight in the northern hemisphere in a year. At this time, the northern hemisphere has the longest day and the shortest night.

When it is absolutely (nearly) straight at noon in summer, there will be a short-term "immediate" phenomenon around the Tropic of Cancer. The pole stands without a shadow, and the sun shines directly on the Tropic of Cancer, which indicates the coming of summer and hot weather and climate near the Tropic of Cancer.