Is there an extreme day or night between the vernal equinox and the autumnal equinox? If so, where is it?

At the equator, only half of the earth's north and south poles are illuminated by sunlight. In these two days, the time difference between sunrise and sunset in the North and South Poles is exactly twelve hours. So there is no extreme day or night anywhere in the world these two days.

The range of a day is related to the latitude of the direct point of the sun, and the latitude difference between the boundary and the pole is the latitude of the direct point of the sun. Therefore, after the vernal equinox every year, there will be an extreme day near the North Pole, and then the range of the extreme day will become larger and larger, reaching the maximum in summer solstice, and its boundary will reach the Arctic Circle.

As we all know, the North and South poles alternate day and night every year. At the pole, six months of the year are day (called extreme day) and six months are night (called extreme night). During the "extreme day", 24 hours a day is daytime. If it is sunny, even at midnight, it is sunny, as bright as broad daylight. When the "polar night" comes, the sun will never rise from the horizon and the stars will always twinkle in the dark night sky.