The alternation of day and night, the reason for the alternation of day and night

The alternating time of day and night is 24 hours, which is a solar day, and it is a mean solar day, which is not the true cycle of the sun's rotation; 23 hours, 56 minutes and 4 seconds is a sidereal day, yesThe rotation of the Earthof the real cycle.

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At any given moment, the diurnal state of the various parts of the Earth can be expressed in terms of the height of the sun. The solar altitude is the solar altitude angle.

, which indicates the inclination of the sun's rays to the local ground level. Everywhere in the hemisphere of the day, the height of the Sun is always greater than 0 degrees, that is, the Sun is on the horizon.

Above; Everywhere along the morning and dusk lines, the height of the sun is equal to 2 degrees, that is, the sun is just above the horizon.

Everywhere in the night hemisphere, the height of the Sun is always less than 0 degrees, that is, the Sun is below the horizon. Because the earth is constantly moving, day and night are constantly alternating. The cycle of day and night, or the diurnal variation of the height of the sun, is 24 hours and is called a solar day.

The solar day restricts human daily life and rest, so it is used as the basic unit of time.

In addition, the short duration of the solar day prevents the entire Earth's surface from heating and cooling too violently, thus ensuring the survival and development of living organisms on Earth.

Due to the rotation of the earth, the day and night conditions at different positions of the earth at the same time are different, some are noon, and some are midnight.

Some experience the morning of the day and night alternate, the dawn.

or in the evening. When the sun rises to its highest position of the day, it shines only on the meridian of that place, which is the local noon. The time thus determined is called local time. For every 15 degrees of longitude, local time differs by 1 hour.

Since the Earth's axis is tilted, the length of day and night varies in different parts of the Earth. In the north and south poles of the earth, the sun shines obliquely throughout the year, and the length of day and night varies the most. In the high latitudes of the northern and southern hemispheres, the sun does not set or does not come out all day long, that is, it is day or night 24 hours a day, which is the "polar day" in the polar region.

and "Polar Night." Phenomenon. At the North and South Poles, there are polar days and nights that last for half a year.

The above content reference: Encyclopedia - day and night alternation

The difference between a sidereal day and a solar day is the difference in the selection of targets, the former is calculated with the star as the target and the latter as the sun, which is the crux of the matter.

The earth is constantly rotating, and at the same time revolving around the sun, and the celestial bodies rise in the east and set in the west, which is actually the phenomenon of the earth's rotation. The cycle of the Earth's rotation, that is, the cycle of the celestial bodies moving on Sunday. The Sun and other stars do not have the same period on Sunday, so there is a difference between the solar day and the sidereal day during the rotation of the Earth.

Sidereal day: When the Earth is located at E1, pay attention to E1, point P and a distant star point A are on a straight line, when the Earth rotates 360°, that is, from E1 to E2, the position of A seems to have reached point B, (actually not moving, because it is too far away) at this time E2, P and B points are still on the straight line, this time is a sidereal day, this time is the real cycle of the Earth's rotation, the time interval (that is, the time between E1, P, A and E2, P, B) is 23 hours, 56 minutes and 4 seconds. Solar Day:

When the earth rotates one week, from e1ps to e2ps, the required time interval is 24 hours, called a solar day, the solar day is not the real cycle of the earth's rotation, but the time interval between the sun passing through the same meridian plane twice in a row, because the earth rotates at the same time, it takes 23 hours, 56 minutes and 4 seconds to rotate for one week, and it takes 3 minutes and 56 seconds to rotate for 59 seconds, and the time, the time used for rotation plus revolution is 24 hours, So a sun is 3 minutes and 56 seconds longer than a sidereal day (about 4 minutes).

The Sun rotates with the Earth.

The earth is a sphere that neither emits light nor is transparent, and the sun can only shine to half of the earth, and the other half cannot shine, it can only be night, so that the phenomenon of day and night is produced (note that it is not the phenomenon of day and night), and the reason for the cycle of day and night is the rotation of the earth due to the existence of day and night phenomena on the earth, and the earth itself is constantly rotating, so the alternation of day and night will occur.

The dividing line (circle) between the half of the day hemisphere and the night hemisphere illuminated by sunlight is called the morning and dusk line (circle).

Introduction of the Earth in the Universe:

Earth is one of the eight planets in the solar system, the third planet in order from near to far, and it is also the terrestrial planet with the largest diameter, mass and density in the solar system, 100 million kilometers away from the sun. The Earth rotates from west to east while revolving around the Sun. Now 4.046 billion years old, it has a natural satellite, the Moon, and the two form a celestial system, the Earth-Moon System.

It originated from the primordial solar nebula 4.6 billion years ago.

Earth is the third planet in the solar system from the inside out, and it is also the terrestrial planet with the largest diameter, mass and density in the solar system, and is the only home for mankind. The human beings who live on the earth often refer to the earth as the world.

The earth is also known as the "earth". The third planet in the solar system close to the Sun is a triaxial ellipsoid with slightly flattened poles and a slightly bulging equator. Surrounded by an atmosphere, the surface is land and sea, with humans, flora, fauna and microorganisms.

The 24-hour alternation of day and night in daily life is due to the self-rotation of the earth (if the earth does not have a rotation, and there is only a revolution, there will also be a day and night.

A: Alternately, but the cycle is not 24 hours). Intuition tells people that the sun rises in the east and sets in the west, making the earth day and night. In fact, the cause of day and night is that the earth is constantly rotating.

Since we are also moving with the earth, we do not feel that the earth is moving, on the contrary, we see the sun moving in the east and setting in the west. In the textbook, "the dawn is ushered in from the east, and the sunset is sent away from the west", which is the movement of the sun as people see, reflecting the rotation of the earth from west to east.

The diurnal phenomenon on Earth is due to the rotation of the Earth and the fact that light travels in a straight line in a homogeneous medium.

"The earth does not move, the sun rotates" The earth will have no day and night, the place where the day is always day, and the place where the night is always night.

The rotation of the earth, the rotation of the sun"The earth will have day and night, and the rotation of the sun will not affect whether there is a day and night phenomenon on the earth.

caused by the rotation of the Earth, while the Sun does not move relative to the Earth. The sun can only reach half a sphere.

The cause of the alternation of day and night – formed by the constant rotation of the earth from west to east;

We experience the alternation of day and night every day, which is caused by the constant rotation of the earth.

If both the Sun and the Earth are electrically charged, when the Sun rotates, it will be affected by the center of the universe, generating a strong rotational current, and this current will produce a rotating electromagnetic field.

At this time, the earth will also generate an induced electromagnetic field to hinder the rotation of the sun's electromagnetic field, and this induced electromagnetic field will promote the rotation of the earth and form the rotation of the earth. Because of the wonderful law of "conservation of angular momentum", all other planets and various celestial bodies today are rotating.

1.Due to the rotation of the earth and the irradiation of the sun, the phenomenon of day and night changes occurs on the earth. To illustrate this phenomenon, the dividing line between the day and night hemispheres on Earth is called the morning and dusk line, which is the line between the sun's rays and the earth's tangent point.

2.The textbook says that at any one time, the sun can only illuminate half of the earth's surface. There are a number of prerequisites here:

First of all, it is believed that the sun is a point of light, and the sun's rays are shining parallel light, which illuminates exactly half of the earth. In fact, the sun is a circular plane with an apparent radius of 16, so that the light from the edge point and the center point of the circle is at different tangent positions on the earth, resulting in different morning and dusk lines, and from the perspective of the sun as a whole, the morning and dusk lines will expand.

3.Second, it is believed that sunlight travels in a straight line to the earth's surface. In fact, the earth is surrounded by a thick atmosphere, and the atmosphere has a refractive effect on sunlight, and the atmosphere can be regarded as a lens, and its refractive index of light is different from the refractive index outside the atmosphere, and the direction of the sun's rays will change when they enter.

Light that does not hit the ground in a straight line will also hit the ground due to refraction, so that the morning and dusk lines may expand again.34 Third, it does not take into account the scattering effect of the atmosphere on light, i.e., the shadow of morning and dusk. It occurs at the edge of the night hemisphere extending about 6°, so that the night is perceived to be shorter than it actually is, and its effect in people's lives is greater than that of the morning and dusk line (16 +34 = 50).

4.In the process of the earth's movement, the earth rotates around the earth's axis, and in the process of rotation, because the earth is an opaque sphere, the hemisphere facing the sun is day, and the hemisphere facing away from the sun is night, the earth keeps rotating, resulting in the phenomenon of day and night. In the process of rotation, the earth's axis is inclined to revolve around the sun, causing the direct point of the sun to move back and forth between and, and the earth's surface at different latitudes to obtain different light and heat, resulting in the change of the four seasons.

Interpretation of day and night.

1) [day and night;Round the clock] day and night day and night day and night business life and death, day and night things also. ——Song Wen Tianxiang, "Guidebook" Afterword, Day and night. ——History of the Ming Dynasty (2) and day and night, day and night.

Guangdong Military Affairs" Detailed Explanation (1).Day and night. The Analects of Zihan:

The deceased is like a husband, reluctant to give up day and night! Tang Yuanzhi's poem "Humanity is Short": "The way of heaven has never lived day and night, and it is busy in spring, autumn, winter and summer.

Lao She's fourth paragraph of "Erma" is suspicious of key nine: "Pastor Yi's face has lost a little weight, because he has broken two dictionaries because he has read Chinese books day and night, and he can't understand it. ”2).

Refers to the two opposing forces of all things, the power of growth and decline, or the two aspects of yin and yang. "Yi Zhi Ci I": The rigid and soft, the image of day and night.

Gao Heng Note: "This cloud day and night is covered with day and night to represent yin and yang. " Yi Zhi Zhi Shang :

It is known by the way of day and night. Gao Heng noted: "Jiao Xun said:

The way of day and night is the way of one yin and one yang. 'Reading is wisdom. This statement of the Book of Changes runs through the law of the transformation of yin and yang opposites and has wisdom, which can predict good luck and evil.

Word decomposition Interpretation of 昼 昼 (昼) ò日: day and night. Daylight (daytime).

Night radical : day; Interpretation of 夜 夜 è the time when it is dark , as opposed to "day" or "day" : night.

Day and night. Nightshade (When the night is coming to an end). Night blindness.

Night. Supper. Night talk.

Night Raid. Nocturnal (妌). Night Fight.

Day radical: Night.

The alternation of day and night is a day, and the rotation of a cluster of Zhou Dan laughing cherry blossoms is a day. So the earth rotates in a circle.

A day-night alternation is formed.

So the answer is one day, one day, the rotation of the earth.

The alternation of day and night once (24 hours) and one rotation is (365 days), so (the rotation of the earth) forms a day-night alternation.

The alternation of day and night is a day, and the rotation of the earth around is also a day, so the rotation of the earth facing the sun forms a day and night cycle.

The alternation of day and night is that the earth rotates for 24 hours, so the earth is sleepy and rotates to form a day and night alternation. The rotation of the earth produces changes in the seasons.

The alternation of day and night is 24 hours. The rotation is also 24 hours. Therefore, the rotation of the cherry blossoms forms a day-night alternation.

In this way, according to my own understanding, I went into the bush and filled in the blanks. I think it's still a relatively smooth and reasonable ruler key, I'm glad about your question, I hope it can help you.

The alternation of day and night is one day, and the rotation of the earth is one day of the week, so it is the rotation of the earth that forms the alternation of day and night, and when the earth rotates, the direct sunlight will be scattered on the rock faces of the earth because of the rotation of the hail against the earth.

The rotation of day and night is 24 hours at a time, and the rotation is 23 hours, 56 minutes and 4 seconds, so the rotation of the earth forms a day and night cycle.

The rotation of day and night is 24 hours, so the rotation of the earth forms a day and night cycle.

The day and night alternate once (one day), and the rotation is one (24 hours), so (the earth) forms a day and night alternation?

The complete addition in these brackets is: the alternation of day and night is a day, and the rotation of the earth's god ball for one week is a day of knowing the opening of the earth, so the rotation of the earth forms a day and night alternation.

Hope, thank you. Take Zheng.

The alternation of day and night is formed by the rotation of the earth, one day and twenty nights are four hours, and the rotation of the earth is one day, so the rotation of the earth forms the alternation of day and night. The earth revolves around the sun for a week, forming a spring cover which summer, autumn and winter.

The alternation of day and night is one day, and the rotation of one week is one day. So the rotation of the earth forms a day-night alternation.

One rotation of the earth is one day, that is, one alternation of day and night, and the rotation of the earth forms a day and night alternation and one revolution is a year.