How does the g value change throughout the year, and what are the reasons for the change in the g va

1. It is well known that the gravitational acceleration of the earth's surface varies with latitude. However, the exact cause of this is a question worth discussing.

Generally speaking, there are no other two factors, one is that the earth's poles are slightly flattened, and the other is the centripetal acceleration caused by the rotation of the earth.

We did the calculations according to the spherical model. According to the final calculation results, if only the g-value difference is considered, then the effect brought by the slightly flattening of the poles is relatively large, and the g-value difference between the poles and the equator is about the same. The difference in centripetal acceleration is only. From this point of view, the change in the g-value is mainly due to the change in the radius of the Earth, and secondarily from the centripetal acceleration.

However, the change in radius does not affect the direction of gravity, and the direction of gravity is "straight down" rather than "pointing towards the center of the earth", which is the effect of centripetal acceleration.

However, the results of the calculations using the spherical model show that the acceleration of the poles is close to that of meters and seconds, which is still different from the actual measurements. We estimate that this comes from two aspects: first, the uneven distribution of the Earth's mass, which is the main aspect; Second, if the ellipsoid model is adopted, the method of calculating the gravitational force will change, and the magnitude of the gravitational force will also vary.

2. At the point where the gravitational acceleration value g, the period of a single pendulum with a pendulum length of l is t 2s. This method of using the mechanical movement of the internal parts of the clock to keep time still has two serious defects: first, with the change of temperature between day and night and the four seasons, the pendulum undergoes thermal expansion and contraction, resulting in the instability of the pendulum length; The second reason is that the gravitational acceleration values at different latitudes and altitudes of the earth are different.

Even at the same point on the ground, the gravitational acceleration value is not a constant value because the earth itself is constantly changing), so that the pendulum clock, which is calibrated by the watch factory, is inaccurate when it arrives at the place of use.

If you have to divide the size of g, then I think g should be larger in winter, because winter is closer to the sun, the earth absorbs more heat, and the overall temperature of the earth is higher, as we all know, from Einstein's general theory of relativity, it can be concluded that gravity is still due to energy (this is not accurate, you can understand it this way is simpler: mass and energy can be similarly transformed, which is the famous mass-energy equation e=mc2) Because there is energy in space, the warping of space-time leads to the generation of so-called gravitational acceleration, and the increase of heat increases the energy possessed by the earth, and the surrounding warp will be a little more (this effect is actually very small), so the gravitational acceleration in winter should also be a little larger, really just a little bit.

If there are other, more obvious effects, they are welcome to be raised, as they are so small

At the poles of the Earth, the g value is the largest, and the equator is the smallest.

What is the g-value you mean? Is it gravitational??? Then the g value varies due to the change of gravitational force, so the closer to the center of the earth, the greater the value, and the farther away from the center of the earth, the smaller the value.

The g-value is related to the latitudinal position of the globe.

The Earth's orbit around the Sun is elliptical and has an angle to the plane of its rotation. When the earth is in different positions of the orbit at different times of the year, different places on the earth receive different solar rays and receive different heat from the sun, so there are seasonal changes and differences in cold and heat.

Climatically, the four seasons are distinguished by temperature. In the Northern Hemisphere, generally speaking, March and May are spring, June and August are summer, September and November are autumn, and December and February are winter.

In the Southern Hemisphere, the seasons are at exactly the opposite time of day in the Northern Hemisphere. When it's summer in the Southern Hemisphere, it's winter in the Northern Hemisphere; It is winter in the Southern Hemisphere and summer in the Northern Hemisphere. There are no clear boundaries between the seasons, and the transition of the seasons is gradual.

The four seasons on Earth manifest first and foremost as an astronomical phenomenon, not only periodic changes in temperature, but also in the length of day and night and the height of the sun. Of course, the length of day and night and the change in the height of the sun at noon determine the change in temperature.

The gradual change of the seasons is not uniform across the globe, with summer in the northern hemisphere and winter in the southern hemisphere; The Northern Hemisphere changes from warm to cold, and the Southern Hemisphere changes from cold to hot. The length of day and night and the height of the sun change periodically in different seasons.

From the spring equinox through the summer solstice to the autumn equinox, the northern hemisphere is in the summer half and the southern hemisphere is in the winter half. During this period, the days are longer and the nights are shorter in the Northern Hemisphere, and the days are shorter and the nights are longer in the Southern Hemisphere; The North Pole is in the polar day, and the South Pole is in the polar night; The height of the Sun north of the Tropic of Cancer is always greater than the mean and south of the Tropic of Cancer is less than the average.

North of the Tropic of Capricorn, the sun rises over the horizon circle in the northeast and sets on the horizon circle in the northwest. On the equinox, the sun rises due east and sets due west all over the world.

From the autumnal equinox through the winter solstice to the spring equinox, the northern hemisphere is in the winter half of the year, and the southern hemisphere is in the summer half. During this period, the length of day and night, polar day and night, and solar altitude in the northern and southern hemispheres were reversed. North of the Tropic of Capricorn, the sun rises over the horizon circle in the southeast and sets on the horizon circle in the southwest.

From the summer solstice through the autumn equinox to the winter solstice, the northern hemisphere changes from summer to winter, and the southern hemisphere changes from winter to summer. During this period, the days in the Northern Hemisphere became shorter, the nights became longer, and the polar diurnal zone gradually shrank. In the Southern Hemisphere, the days are getting longer, the nights are getting shorter, and the polar night zone is shrinking. The height of the Sun decreases north of the Tropic of Cancer and increases south of the Tropic of Capricorn.

North of the Tropic of Capricorn, the rising direction of the sun changes from northeast to southeast, and the direction of falling changes from northwest to southwest. The autumnal equinox rises due east and sets due west.

On the equinoxes of spring and autumn, the length of day and night and the height of the sun are equal to the average of the whole year around the world, and have the typical characteristics of the transition from maximum (or minimum) to minimum (or maximum). Therefore, it is very reasonable to use the spring equinox as the midpoint of spring, and the autumn equinox as the midpoint of autumn; In summer, the days are the longest, the nights are the shortest, and the highest solar height is on the day of the summer solstice, when the surface receives the most solar energy. So, it makes sense for the summer solstice to be the midpoint of summer; In the same way, the winter solstice is also very scientific as the midpoint of winter.

The administrator is here to answer the question :)

Hehe, let me tell you, keep it simple.

There are four seasons in a year, mainly because of the result of the earth's revolution, in the process of the earth's rotation around the sun, according to the distance from the sun, as well as the declination angle of the earth's rotation, resulting in the alternation of cold and hot north and south on the earth's surface, resulting in the appearance of the four seasons on the earth's surface, but due to the declination of the earth's rotation, in the same season, different phenomena will appear on the earth.

The Earth is like a spinning top, it rotates around its axis of rotation constantly, and each revolution is a day. The rotation creates the phenomenon of day and night, with day on the side facing the sun and night on the side facing the sun. When we in China are here in the daytime, the United States on the other side of the world is exactly at night; The direction of the Earth's rotation is from west to east, so we see the sun, moon and stars rising from the east and gradually descending to the west.

Not only does the Earth rotate, but it also revolves around the Sun. The orbit of the Earth's revolution is elliptical, the semi-major diameter of the orbit is 149,597,870 km, the eccentricity of the orbit is about, one revolution is one year, the average speed of the revolution is 29 79 kilometers per second, the angle of intersection between the orbital plane and the equatorial plane is about 23°27', and there are periodic changes The combination of the Earth's rotation and revolution produces the alternation of day and night, the change of the seasons and the distinction of the five zones (tropical, north-south temperate zone and north-south cold zone) on the earth.

Since the Earth's axis of rotation is obliquely intersected with the plane of its orbit at an inclination angle of about 66°33, during the year when the Earth revolves around the Sun, sometimes the northern hemisphere of the Earth is inclined towards the Sun, and sometimes the southern hemisphere is inclined towards the Sun (left). In short, the direct point of the sun always moves between the Tropic of Cancer, resulting in a change in the length of day and night and the alternation of the seasons.

In astronomy, the four seasons begin with the spring equinox, summer solstice, autumn equinox, and winter solstice, but the seasons divided in this way cannot fully reflect the phenological signs of each season in each place. Therefore, our ancestors divided the year into 24 solar terms, each of which was divided into 3 seasons. The climate is also divided into four seasons by the average temperature of the weather (5 days for each weather).

The average temperature of 10 is winter; 22 o'clock is summer; The average temperature is between October and 22 o'clock in spring and autumn.

The main reason is that the earth is tilted and rotated. Although the Earth's orbit is an ellipse, this ellipse is very close to a perfect circle. The distance of the Earth from the Sun does not change much during the year, which is not the reason for the change of seasons.

The point is that the earth is tilted and rotated, and the angle of inclination is 23 degrees and 26 minutes. The existence of this angle causes the point of direct sunlight to move during the year, which in turn causes the change in the altitude angle of the sun on the ground. And the change in the angle of the sun's altitude causes a change in the heat received by the ground.

This is the reason for the formation of the four seasons.

Because the plane of the Earth's revolution is 23°26 between the equator.

There are four seasons in a year, and the key is because the earth's axis has declination. If there is no tilted declination, the sun will always shine perpendicular to the equator, and the Chinese mainland will always be spring.

Why does the Earth's rotation have declination? That's because of the moon, after the earth grabbed the moon, it was led astray by the moon

Suppose the Earth is a sphere.

The gravitational force of the object is formed due to the attraction of the earth, to be precise, gravity is a component of the gravitational force (the magnitude is unchanged: gmm r 2), the gravitational force is decomposed into gravity and centripetal force, and due to the coaxial rotation, the angular velocity w is equal at any place on the earth's surface, so the centripetal force f=m*w 2*r = m*w 2*r*cos (is the angle between the line between the point and the center of the earth and the plane of the equator).

In the process from the North Pole to the equator, it gradually decreases and the centripetal force gradually increases. g=(f million 2 + f direction 2-2*f million * f direction *cos ) 1 2) = 1 2). Because at the equator, the centripetal force is less than the gravitational force, i.e., m*w2*r, so the gravitational force gradually decreases.

Therefore, the gravity at the poles is the largest, and the gravity at the equator is the smallest.

1. There is an angle (23°26) between the axis of rotation of the earth and the earth's orbit around the sun (ecliptic plane), so when the earth revolves around the sun, the position of the sun directly on the earth will change, from 23°26 south latitude (Tropic of Cancer) to 23°26 north latitude (Tropic of Cancer).

When the sun is directly shining, the heat obtained by the earth's surface is high, and the temperature is high, which is summer; Conversely, when the sun is obliquely shining, the heat gained from the earth's surface is low, which is winter. When the sun shines directly into the Northern Hemisphere, it is summer in the Northern Hemisphere and winter in the Southern Hemisphere; Conversely, when the sun shines directly into the Southern Hemisphere, it is summer in the Southern Hemisphere and winter in the Northern Hemisphere.

When the sun reaches the Tropic of Capricorn, the winter solstice (around December 22) and the summer solstice (around June 22) are respectively. When the sun reaches the equator, the spring equinox (around March 21) and the autumn equinox (around September 21) are respectively.

2. The four seasons of the year, that is, spring, summer, autumn and winter, each season is 3 months. Not only is the climate very different from region to region on earth, but the climate is also different in different seasons in the same region. Such as:

The fourth fold of Yuan Guan Hanqing's "Lu Zhailang": "I am a monk all year round, spring, summer, autumn and winter, so happy!" ”

The earth revolves around the sun, and the temperature of the earth varies depending on the distance, and the four seasons are formed.

What your friend said is in line with the lunar calendar, that is, January to March is spring, April to June is summer, July to September is autumn, and October to December is winter. Why is August 15 called Mid-Autumn Festival in China? Is the Mid-Autumn Festival just called?

Of course, because August 15 is the middle day of autumn! August is also called mid-autumn. Because the lunar calendar is the calendar that originated in China, it is compiled according to the general habits of ancient people's farming, and at the same time, it also helps and reminds people to adapt farming to the times.

The Gregorian calendar used now is derived from the West, and Jesus probably has nothing to do with China, and it is certainly not in tune with the Gregorian calendar months to divide China's own seasons. The Spring Festival of the Gregorian calendar is generally around February 5, that is, it is more than a month earlier than the lunar calendar. Nowadays, the division of seasons is calculated according to two minutes and two solstices, but in ancient times, I was afraid that there was no such high technology, and some other methods were used to measure to determine the years and months.

Due to the low level of science and technology in ancient times, the division of the year should not be particularly accurate, so there should be some subtle differences between the current lunar calendar and the ancient lunar calendar, but the approximate time and solar terms are correct, and they will not be too different.

For example, there is a proverb: Spring beats six or nine heads, that is, the first day of six and nine, is the beginning of spring.

It is true that it is customary to divide the month as you say the month is spring, and so on.

The spring equinox is March 21, the summer solstice is June 22, the autumn equinox is September 22, and the winter solstice is December 21, according to this division.

The above division is basically correct for the northern hemisphere.