When can I see the "pole without shadow"

"The vertical pole has no shadow" phenomenon, that is, the sun shines directly at noon, which leads to the phenomenon that objects have no shadow. This phenomenon usually occurs in the area north of the Tropic of Cancer.

In the northern hemisphere, the summer solstice will have the longest day and the shortest night of the year. On this day, the sun shines directly on the Tropic of Cancer, which is 23.5 degrees north latitude. In the area north of the Tropic of Cancer, the altitude angle of the sun reaches the maximum, that is, 90 degrees. When the sun shines vertically on the ground, there is no shadow on the object, which is the phenomenon of "no shadow on the pole"

However, the summer solstice is not the only solar term with the phenomenon of "standing upright without shadow". As long as the sun shines directly to the area north of the Tropic of Cancer, this phenomenon will occur. For example, on the solstice in winter, although the day is the shortest and the night is the longest in a year, there will also be a phenomenon of "no shadow on the pole" in the area north of the equator.

It should be noted that the phenomenon of "extremely shadowless" is not absolute, but the length of the shadow is very short, and it may even be invisible to the naked eye. This is because when the sun shines on the ground, the height and shape of the object will affect the length and shape of the shadow because of the angle.

In short, the area north of the Tropic of Cancer, such as the area north of the equator, may be "extremely shadowless" at any time. However, many other factors need to be considered in order to truly realize "infinity", such as the height angle of the sun, the shape and height of objects and so on.