Polar day and polar night judgment, where the polar day and polar night phenomenon appears

Only areas north of the Arctic Circle and south of the Antarctic Circle can experience polar day and night phenomena.

Because the earth is a huge sphere, its own density is very large, opaque, so when irradiated by sunlight, only half of the earth is illuminated called the day hemisphere, and the other hemisphere is illuminated at the end of the night hemisphere.

Assuming that the day and night hemispheres are on the same meridian (divided into 360 degrees of latitude) and that both span only 180° latitude (in fact, since the Sun has an apparent radius of 16, and the horizon rays have a refractive difference of 34, the day hemisphere is greater than the night hemisphere at any time, but since the difference is not large, we can roughly assume that both hemispheres span 180 degrees of latitude each), then the height of the Sun is 0° on both parallels (tangent to the morning and dusk lines) 90 degrees from the direct point of the Sun, Among them, the meridian where the direct point of the sun is located is the height of the sun at noon (that is, the latitude coils from this latitude to the pole are all in the night hemisphere - the height of the sun at noon is less than or equal to 0°, and the polar night appears), and the other meridian directly opposite the meridian where the direct point is located is the solar height at midnight (that is, the latitude coils from this latitude to the pole are all in the day hemisphere - the height of the sun is equal to greater than 0° at midnight, and the polar day appears).

According to the above reasoning, it is not difficult to understand: at what latitude the direct point of the sun is, and the latitude coil that leaves the pole is equivalent to this latitude to the pole to the pole is the range of the polar day and night phenomenon at this time. The hemisphere where the direct point of light is located, this range is the polar day; In the other hemisphere, this range is the polar night.

Therefore, the method of finding the polar day and night range of the known position of the direct sun point is to directly subtract the latitude of the direct point from 90° to obtain the occurrence range, and then determine the polar day and polar night according to the relationship with the position of the direct point. For example:

When the sun shines directly at 5°N, the north of 85°N is the polar day, and the south of 85°S is the polar night. If the direct point is at 20°s, then the south of 70°s is the polar day, and the north of 70°N is the polar night.

If the duration of the day or night lasts for a long time, such as half a year, it is the polar day or the polar night.

Of course, it can be simply understood as day or night at the North Pole or the South Pole.

Definitely on the high school geography books! On the summer solstice, the North Pole is on the pole day, and the Antarctic is on the night. On the winter solstice, the Antarctic polar day and the Arctic polar night

The earth is oblique, the earth is rotating, and when it turns to a certain extent, there is a polar day and a polar night

Polar day is daytime.

Otherwise, it's a dark day.

The phenomenon of polar day and night occurs in the Arctic and Antarctic Circles.

Polar day and night are natural phenomena in the polar regions of the earth, the so-called polar day, that is, the sun never sets, the sky is always bright, this phenomenon is also called white night; The so-called polar night is the opposite of the polar day, the sun never comes out, and the sky is always dark.

In the high latitudes of Antarctica, there is no "sunrise and sunset" rhythm of life, and there is no 24-hour day and night cycle.

Both polar day and polar night occur in the Earth's Arctic and Antarctic Circles. Iceland.

Norway, Sweden.

Finland, Russia, Alaska in the United States.

Canada, Greenland.

There is a polar day or polar night phenomenon. Polar day and polar night are peculiar natural phenomena that can only be seen in the Arctic and Arctic circles.

The phenomenon of polar day and polar night only occurs in the Antarctic and Arctic circles, and when there is polar day, there is no night for half a year, and when there is fluid accumulation, there is no day for half a year.

The reason for this peculiar natural phenomenon is that the direct sunlight points on the earth will move north and south, and some areas at the top of the north and south of the earth will either be irradiated by sunlight for a long time or no sunlight for a long time during a certain period of time, so that the phenomenon of polar day and polar night is formed.

During the spring and autumn equinoxes of each year, sunlight will shine directly on the equator, when the length of day and night at the north and south poles is equal, but after the spring equinox, the direct sunlight point will move to the north, and the polar day and polar night phenomena will occur in the Antarctic Circle and the Arctic Circle at the same time.

After the vernal equinox, polar daylight occurs near the Antarctic Circle; After the autumn equinox, the polar night phenomenon occurs near the Arctic Circle.

During each year, polar day and polar night phenomena alternate between the North and South Poles. About half of the year is the polar day, and half the year is the polar night.

<>The picture above is the Arctic region**, which is seen from the sky above the North Pole, with the Arctic Ocean, North America and the coastal areas of Asia and northern Europe. The land part of the Circumarctic consists of Russia, the United States, Canada, Denmark, Norway, Iceland, Sweden and Finland. The main sea areas are the Greenland Sea, the Norwegian Sea, the Pakistani Lunts Sea and the Bering Sea.

The picture above is the Antarctic region**, the Antarctic continent is a separate plate surrounded by the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean, forming a huge hydrosphere around the Earth.

Polar day: In the Antarctic region, the phenomenon that the sun never subsides into the horizon within 24 hours of the current earth time is called polar day. At the South Pole, half of the year is the polar day; If refraction and positive action are taken into account, it should be a little more than half a year for a few days.

The polar day at the South Pole occurs during the summer half of the Southern Hemisphere.

Polar Night: In contrast to the polar day, in the Antarctic region, the phenomenon that the sun is always below the horizon for 24 hours local time is called polar night. At the South Pole, half of the year should be spent in the polar night; If refraction is considered, it should be less than half a year.

The polar night at the South Pole occurs at the exact opposite of the polar day, during the winter in the Southern Hemisphere.

In Antarctica, the duration of the polar day and the polar night becomes shorter as the latitude decreases, and on the Polar Circle, the polar day and the polar night occur for only one day.

The polar day and night phenomena occur north of the Arctic Circle and south of the Antarctic Circle, i.e., the North and South Arctic Zones.

Polar-day and polar-night are natural phenomena in the polar regions of the earth. The so-called polar day means that the sun never sets, and the sky is always bright; The so-called polar night is the opposite of the polar day, the sun never comes out, and the sky is always dark. In the high latitudes of Antarctica, there is no "sunrise and sunset" rhythm of life, and there is no 24-hour day and night cycle.

Polar day and polar night are natural phenomena unique to the Polar Circle. Occurs in the Arctic Circle (66°34 N') and the Antarctic Circle (66°34 south latitude') to the south.

The formation of the polar day and the polar night is caused by the rotation of the earth around its own inclined axis as it orbits the sun in an elliptical orbit. It turns out that when the Earth rotates, the Earth's axis forms a 23°26 with its perpendicular line'the angle of inclination; Therefore, when the earth revolves, there is a continuous period of 6 months, and one of the poles always faces the sun, and it is all daytime; The other pole is turned away from the sun, and it is all night. The North and South Poles are amazing natural phenomena that no other continent has.

Related Notes:

Every year in the north and south poles, "polar day" and "polar night" alternate. There are roughly 6 consecutive months of day (called polar day) and 6 months of night (called polar night) in a year. The period of alternation of day and night changes with increasing latitude, and the higher the latitude, the longer the period of polar day and polar night.

Between the polar circle and the pole, the closer to the pole is the length of the day and night, the closer to the pole, the closer to the pole, the closer to the pole, the closer to the pole, the closer to the pole, the closer to the day, the closer to the pole. That is, in areas within the Polar Circle, the length of the polar day and polar night varies depending on the latitude. In Antarctica, the period of occurrence of polar day and polar night becomes shorter as the latitude decreases, and on the Polar Circle, the polar day and polar night both occur for only one day.

If you leave the South Pole, the lower the latitude, the more day or night it is, and the period of polar day and night will gradually shorten. At 80°S, there are times when the day and night change occur within 24 hours of a day, except for the polar day and the polar night. If you are at the end of the polar day, the period of darkness is very short at first, and then the period of darkness becomes longer and longer, until finally it is all night, and the polar night begins.

And in the Antarctic Circle (66°33 S'There is only one full day (24 hours) of the year that is all day and one full day is all night. China Antarctic Great Wall Station (62°13 south latitude'Outside the Antarctic Circle, at one or two o'clock in the middle of the night in December, the sky is still cloudy, and you can read and write with good eyesight. The natural phenomenon of polar day and night also occurs at the North Pole, the other pole of the Earth, but at the opposite time of the South Pole.

If the North Pole is in the polar day, the South Pole is in the polar night, and vice versa.

The above content reference: Encyclopedia - Polar Day and Polar Night.