The problem of the length of a day compulsory in geography, how to calculate the length of a day in

The length of the day and night varies with the seasons, but the sun must be 12 o'clock overhead, and the length of the day varies because the sunrise and sunset are different.

It's like you standing at twelve o'clock, counting n hours forward, and the sun rises; N hours later, the sun sets. Then the daylight is 2n hours.

In fact, 12 o'clock is indeed mid-day time, which is true solar time. It's just that if that's the case, 12 o'clock is different every day, you don't understand.

This is because the longitude varies from place to place. The difference between the daytime at 120°E and the midday at 105°E is exactly 1 hour.

For the sake of convenience, our country stipulates that Beijing is located in the East Eighth District (120 east longitude is the 15 ° range of the middle line, that is, the time from east longitude to east longitude is the legal time, which is called Beijing time.

Half of the day must be 12 o'clock local time (i.e., local time), and half of the sunset time minus the sunrise time is 12 noon.

...Sunrise and sunset are related to latitude in addition to latitude. It's also about altitude.

Half of the day. Theoretically, it's 12 points. But if the altitude is low, such as Shanghai, the sunrise will be later.

The Tibetan Plateau is earlier.

Because this time is China's unified time - Beijing time.

The length of the day hits the bending and infiltrating hours, the number of day arcs, and the number of degrees of the day, and the slap ridge.

Day length pants 2* (12-sunrise time).

Day length 2*(sunset time -12).

Day length = sunset silver mountain grip time - sunrise time.

Day length = 24 hours - night front keelong.

Day length = 15° hours of longitude spanned by the diurnal arc.

At the vernal equinox, the sun shines directly on the equator, when the earth equinoxes day and night.

Gradually, the earth runs towards the summer solstice, and the direct sunlight also moves northward until the Tropic of Cancer, at this time the days in the northern hemisphere of the earth are getting longer, after the summer solstice, the earth runs towards the autumnal equinox, and the sun runs back to the equator from the Tropic of Cancer.

This process from the spring equinox to the summer solstice and then to the autumn equinox is one of the examples you said that the summer solstice is the point of symmetry, for example, if it is the summer solstice, you imagine it as the origin, and the two days are equal in time (such as the same length as the day, of course, there is a condition, that is, you must be comparing at different times in one place, not two different places.

Because the spring equinox (March 21) and autumn equinox (September 23) are directly on the equator, the whole world is in the equinox; On the summer solstice (June 22), the sun shines directly on the Tropic of Cancer (23°26 N), and the polar day phenomenon occurs north of the Arctic Circle. In the south of the Antarctic Circle, the polar night phenomenon occurs in the southern hemisphere, and the days are short and the nights are long in other southern hemisphere regions except for the equinox of day and night in the southern hemisphere (December 22), when the sun directly hits the Tropic of Capricorn (23°26 s), the polar day phenomenon occurs south of the Antarctic Circle. The polar night phenomenon occurs north of the Arctic Circle, and the days are short and the nights are long in the northern hemisphere.

10 The difference in day length is the largest, indicating that "day length A-day length B" is the largest, and the day length in the northern hemisphere is the longest and the southern hemisphere is the shortest on the summer solstice, so the difference in day length is the largest.

11 a = the length of day A - the length of day B, to be the largest in a, that is, to be the largest in A, and the smallest in B. The longest day length is 24 hours, that is, within the polar circle, the day length of the polar day is 24 hours; Because they are in the same hemisphere, the shortest day length in the hemisphere where the polar day occurs is 12 hours, that is, it is above the equator.

Because the hemisphere day length of the polar night is less than 12 hours).

12 Shea is located in the northern hemisphere, and since a>12, B must be in the southern hemisphere. The difference in day length between the two places at point P is 0, and because the difference is the largest after point P, it means that point P is the day of the vernal equinox (Northern Hemisphere). During the period of p n (Northern Hemisphere equinox-summer solstice), b and c pairs.

And then let A be in the Southern Hemisphere, because A>12, so B must be in the Northern Hemisphere. The difference in the length of day between the two places at point P is 0, and because the difference is the largest after point P, it means that point P is the day of the spring equinox (the southern hemisphere equinox, which is the northern hemisphere autumnal equinox). During the period of p n (Northern Hemisphere Equinox-Winter Solstice), a, c pairs.

To sum up, c pairs.

10.If A is in the northern hemisphere and B is in the southern hemisphere, then the n date is (b)aEquinox Day BSummer Solstice cAutumnal Equinox Day DWinter solstice day [the days in the Northern Hemisphere are longer than those in the Southern Hemisphere, and the difference is the largest].

11.If A and B are in the same hemisphere (north or south), the maximum value of A is (B) hours [in extreme cases, a point in the Arctic Circle (there is a polar day and a night) vs the equatorial region is slightly different (the day and night are equinoxical all year round), the difference is 12 hours].

12.If a>12, in the time period of p n, the noon shadow (c) aNorth-facing b

South-facing cLengthened dShortening [a>12 can determine that the latitudinal difference between a and b is very large, and it can be determined that b is located in the southern hemisphere.

p n is the spring equinox to the summer solstice phase, and shadow growth in the southern hemisphere is certain. After figuring it out, the wrong option for B is that the sun can't rise at noon, and there is no shadow. Even if there is a shadow, it is not to the south (the logic of the high school exam has been almost forgotten after a few years)].

Sunrise is about 4:30 o'clock, so day length = 2 (

The day length of a point on the morning and dusk line is calculated by dividing the number of degrees of longitude spanned by the parallel line on which the point is located divided by 15 degrees.

From this, it can be seen that A is 15 hours, B is 18 hours, and C is 24 hours.

<> comparing the sunrise time difference between the two places, if the two places are on the same meridian, the curve of the time difference chart should be a complete approximate sinusoidal curve (blue line in the above figure) over a year. The difference between the sunrise at d, m and d' is theoretically 0, and the solar term is a diquinox. Point C is the summer or winter solstice.

The daily difference between the two places accounts for half a year.

However, the curve does not reflect the above characteristics, when we translate AD to A'D' to get the complete curve, then it can only show that A and B are not the same longitude.

When the translation obtains the complete curve, it is actually to let A and B converge on a meridian line (see the coordinates on the right). According to the above description, d, m, and d' are located on the equinox (the difference between the sunrise is an hour, but in fact the longitude must be 9°, and A is located to the west of B). c is the second solstice.

So option d is correct.

In winter, the days are short and the nights are long in the northern hemisphere, and the days are longer and the nights are shorter in the southern hemisphere. Keep this judgment in mind and pull it.

The Earth's revolution changes in 4 seasons, and the length of day and night changes.

1) The day length is 15 hours, and the sunrise time at point A is 6 o'clock, and Beijing time is 2 o'clock at this time. The altitude of the Sun at point B is 68°26'.

Analysis: Obviously, it can be seen from the figure that the diurnal arc (non-shaded part) occupied by point b is 225°, and according to the formula, daytime length = diurnal arc 15°=15 hours; Point A is located on the equator and the sunrise and sunset are fixed regardless of the season, 6 o'clock and 6 o'clock. Beijing time is 120 °E, very simple, from the figure can be seen that 90 ° E is also in the hemisphere part on the right (according to the east longitude along the silver holding the direction of the earth's rotation to judge), at this time 90 ° E is also on the midpoint line of the hemisphere, it is 0 o'clock, the front is absolutely with the difference of 30 ° between Beijing 120 ° and 90 degrees, then the time is plus 2 clocks, that is, 2 o'clock.

The formula for calculating the height of the sun is: the height of the sun at noon at point b = 90° - (45 ° - 23 ° 26 ') = 68 ° 26 '.

2) Subtropical high pressure, dry weather, high temperature and little rain. I don't need to explain this question??? Just remember that in July 78 every year, the middle and lower reaches of the Yangtze River are controlled by subtropical high pressure, and there is a drought, high temperature and little rain.

3) South, lighting and ventilation, minimal. Just remember that you can get sunlight when you look at the place where the light shines. In summer, the Northern Hemisphere is at its highest, and the higher the altitude, the smaller the area of light that hits the room.

The height in winter is small, the angle is smaller than in summer, and the oblique line irradiates the indoor area. I don't know how to ask questions. -Wise.

Hello: First of all, this is a hemisphere, and what we see is only half of the day and night. The result is x2.

Secondly, to find the day length of a certain point, look at the length of the day arc where the point is located.

So how do you see the length of the diurnal arc?

We can cross this point and make a line parallel to the equator. Look at how long the part is during the day.

Then, in this problem, we can see that the length of the diurnal arc where point C is located spans 5 blocks. There are 6 squares in this diagram, and a total of 180°. So, a lattice 30 degrees, two hours.

ソ, 5 cells take 10 hours. As we said at the beginning, this is a hemisphere, and if you multiply it by 2so, the day length is 20 hours.

I'm glad to answer for you, please ask if you don't understand, thank you.

1. The same latitude, the length of day and night is the same.

2. Find the intersection of the latitude line and the morning and dusk line, and the intersection point with the morning line is the sunrise, and calculate the sunrise time; The intersection point with the dusk line is sunset, and the sunset time is calculated.

3. Apply the formula: day length = 2 (12 - sunrise) = 2 (sunset - 12) I hope it will help you.

According to the latitude and longitude line and the morning and dusk line, the intersection point of the equator and the morning line is 6 o'clock, the intersection point of the dusk line is 18 points, the intersection point of the middle meridian and the equator is 12 points, according to the ratio of the length of the day and night arc to compare and judge, half of the earth is 12 o'clock, and the hour is judged according to the number of meridians.

The morning and dusk line and the polar circle are cut first, the polar day of the Arctic Circle, which is the summer solstice, point C is located in the northern hemisphere, and the day is longer than the night.

Isn't that the Tropic of Capricorn? That is, the Tropic of Cancer day length: 14 hours and 16 minutes.

Hopefully it can be adopted.

Daylight length = 15 degrees of longitude spanned by the diurnal arc.

The length of the night = 15 degrees of longitude spanned by the night arc.

First find the morning and dusk line, which is the line that separates day and night, which is generally marked on the chart. Find the place to be calculated, and see how much longitude he passes through the day, 15 degrees is an hour, but the length of the day can be obtained, and the sunrise and sunset can be found.

Knowing the longitude spanned by the day and night arcs (see how much longitude it passes through during the day), find the length of the day and the length of the night.

Day length = sunset time - sunrise time; = (12-sunrise time) x2; = (sunset time -12) x2; 24- Night long.

For example, if the sun rises at 5:00 in a certain place, its day length is 14 hours.

The hour is 14 hours and 16 minutes.