Why is there a diurnal cycle?

The rotation of the earth produces a diurnal cycle;

The Earth's revolution produces seasonal changes.

Since the earth is an opaque planet, the sun and stars give the earth light, and the side that shines on the sun is day and the other side is night. The earth is constantly rotating from west to east around its axis of rotation, and the phenomenon of celestial bodies rising in the east and setting in the west is a reflection of the earth's rotation. One rotation of the earth is equivalent to the week when the sun rises in the east, sets and rises again, and it is also our daily day.

As the Earth rotates, it revolves around the Sun, which rotates from west to east. The orbit of the Earth's revolution is an ellipse that is close to a perfect circle, and the Sun is located in a focal point. The Earth's orbital period is one year, and astronomically it is 365 days, 5 hours, 48 minutes and 46 seconds.

The angle between the Earth's orbit (ecliptic plane) and the Earth's rotation plane (equatorial plane) is 23 degrees 26 minutes, which causes the direct point of the Sun to move between the Tropic of Cancer in a one-year cycle, forming the four seasons in temperate regions.

On March 21 every year, the direct sun point moves from south to north to the equator, and the global day and night are equinox, which is our vernal equinox day, and on June 22, the direct sun point moves north to the Tropic of Capricorn, becoming the longest day in the northern hemisphere, which is what we call the summer solstice, and then the direct sun point turns to move south, and on September 23, it hits the equator directly, which is the autumnal equinox, and on December 22, it moves to the Tropic of Capricorn, and it is our winter solstice.

The change of seasons is actually the result of the combined effect of the earth's rotation inclination and revolution around the sun, without one of these conditions, the change of seasons will not occur, and everything on the earth will change accordingly.

Stupid, if there was no night, the boss of the lighting equipment would go bankrupt, so there was a day and night change.

The rotation of the earth produces a diurnal cycle;

It refers to the phenomenon of alternating day and night produced on the earth by the rotation of the earth, with a cycle of one solar day (24 hours).

Since the earth does not emit light and is opaque, at the same time, the sun can only illuminate half of the earth's surface, towards the sun's hemisphere, called the day hemisphere, which is daytime. The other hemisphere with the sun on its back, called the night hemisphere, is night. Because the earth is constantly rotating from west to east, the day and night hemispheres and the morning and dusk line are also constantly moving from east to west, so that the alternation of day and night is formed.

If the earth does not rotate, the cycle of day and night on the earth will be one year, in which case the thermal balance of the earth's surface, as well as air pressure, air currents, evaporation, water vapor condensation, and the conditions of the organic world, will all undergo completely different changes than now, such as excessive heat and cold making it difficult for organisms to exist, and huge temperature differences between day and night can cause strong storms.

Because the rotation of the earth takes one solar day as the rotation period, the diurnal cycle is 24 hours, so that the sun can evenly heat the earth, creating a better living environment, and also making all life activities and various physical and chemical processes on the earth have obvious diurnal changes. Thus ensuring the survival of living organisms on Earth and preventing all other processes from developing in extreme directions.

What is the impact of the alternation of day and night on the formation and development of life on Earth:

1) It is precisely because of the periodic alternation of day and night that the temperature of the earth's surface is neither too low nor too high, creating certain conditions for the formation and development of life on the earth.

2) The cycle of day and night provides convenience for animals to recuperate, and brings the possibility of photosynthesis and nutrient storage for green plants on the whole earth.

The day-night cycle is caused by the rotation of the Earth.

The Earth rotates from west to east on its axis of rotation, rotating counterclockwise from the North Pole and clockwise from the South Pole. The reason for the alternation of day and night on the earth is mainly because of the rotation of the earth.

The Earth's axis of rotation is angled to the ecliptic plane, perpendicular to the equatorial plane. The Earth's rotation is an important form of motion of the Earth, with an average angular velocity of rotation in degrees and a linear velocity of 465 meters at the Earth's equator. It takes 23 hours and 56 minutes for the Earth to rotate around and increases or decreases by 3 thousandths to 4 thousandths of a trillion seconds every 10 years.

The alternation of day and night is a natural phenomenon. The earth is a non-luminous and opaque sphere, and the sunlight can only illuminate half of the globe at the same moment, and the half of the globe illuminated by sunlight is day, and the half of the globe that is not illuminated by sunlight is the dividing line (circle) between the night, day hemisphere and the night hemisphere, which is called the morning and dusk line (circle).

The principle of the formation of the Earth's rotation

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.

To use a simple analogy, the rotation of a figure skater slows down when the arms are extended, because the radius of the rotating body increases, and the angular momentum is conserved, and its linear velocity inevitably decreases; Conversely, if the arms are folded together, the rotation speed increases. It is precisely because of the wonderful law of "conservation of angular momentum" that all other planets and various celestial bodies today are self-rotating.

It wasn't until Copernicus proposed that the Earth is also a planet, orbiting the Sun while rotating itself on its axis, that the principle of the alternation of day and night was understood.

The above content reference: File chain rent encyclopedia - day and night alternation.

The day-night cycle is caused by the rotation of the Earth.

The day-night cycle is caused by the rotation of the Earth. The earth is a non-luminous and opaque sphere, the sunlight can only illuminate half of the globe at the same moment, the half of the globe illuminated by sunlight is day, and the half of the globe that is not illuminated by sunlight is night, and the dividing line between the day hemisphere and the night hemisphere is called the morning and dusk line. The discovery of the phenomenon of day-night alternation depends on the Copernican heliocentric theory.

Due to the rotation of the earth, the situation of the eve of the day at the same time is different at different positions of the earth, some are noon, some are midnight, and some are experiencing the alternation of day and night in the morning, dawn or 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, there is a 1-hour difference in local time.

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-latitude areas 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 phenomenon of "polar day" and "polar night" in the polar region. At the North and South Poles, there are polar days and nights that last for half a year.