A, the type of sunshine map
(1) Side view of the earth, which is the most common sunshine map. Generally, the north pole is above, the south pole is below, the equator is centered on a straight line, and the earth axis is vertical or inclined; The meridian represents the arc on the map, and the latitude represents the straight line; The termination line is a straight line perpendicular to the sun's rays and bisecting the equator (the termination line is always perpendicular to the sun's rays); On the vernal equinox, the termination line starts and ends at the North Pole and the South Pole; From No.2 to No.3, the termination line is tangent to the South Arctic Circle (the termination line starts and ends at both ends of the South Arctic Circle). (see figure 1, 2, 3)
(2) polar top view, the center is polar, the outer circle is equator (some are latitude circles), the ray is longitude, and the concentric circle is latitude, which can be divided into north pole map and south pole map. In vernal equinox, the termination line is a straight line (coincident with two opposite meridians), which passes through the pole and divides the day and night equally; On the second solstice, the termination line is an arc tangent to the South Arctic Circle. (See Figures 4, 5 and 6)
(3) Rectangular projection, which enlarges the north and south poles to the length of the equator, has great distortion with the actual situation. The judgment is mainly based on the fact that the polar days and nights of the Terminator line and the polar circle are equally divided on the equator, and the sunrise and sunset times are 6 o'clock and 18 o'clock respectively. (as shown in fig. 7)
Second, the problem-solving skills and hidden rules of sunshine map
1. Determine the North Pole and South Pole
① Side view, usually up north and down south.
② From the direction of rotation, counterclockwise rotation is the North Pole, and clockwise rotation is the South Pole (from north to south).
③ From the arrangement of longitude degrees, the rotation direction is the same as the arrangement direction of longitude degrees from small to large (or the same as the arrangement direction of longitude degrees from large to small).
2. Determine the east-west longitude and east-west direction
① Take longitude 0 as the baseline, and turn from west longitude to east longitude according to the rotation direction of the earth, that is, left west longitude and right east longitude.
② Along the rotation direction of the earth, the degree increases eastward and decreases westward.
③ For the same longitude value, the east longitude value in the east is large, and the west longitude value in the west is large.
(4) With different longitude values, the east-west direction can be identified by the sum of the east-west longitudes of the two places: (a) If the sum of the longitudes of the two places is less than 180, the east longitude is in the east and the west longitude is in the west; B. If the sum of the longitudes of the two places is greater than 180, the west longitude is in the east and the east longitude is in the west; C If the sum of the longitudes of the two places is equal to 180, then the two places are located on opposite longitudes, so it is ok to say which point is in the east and which point is in the west. In this case, the east and west directions cannot be compared. That is to say, to judge the east-west direction, first select the lower arc segment (the arc segment with the difference between the two places less than 180), and then determine the orientation according to the rotation direction of the earth from west to east.
Determine the termination line
The terminator line is the dividing line between the day and night hemisphere formed by the sun shining on the earth's surface. It is composed of morning line and faint line, so it is also called morning faint circle. If the scattering effect of solar light is not considered, the morning and evening circle is a circle (passing through the center of the earth) and always perpendicular to the sun.
① On the sunshine chart, along the rotation direction of the earth, the dividing line from the day hemisphere to the night hemisphere is a dark line (Figure 6BC), and the dividing line from the night hemisphere to the day hemisphere is a morning line (Figure 5AC).
② According to the judgment of the day and night hemispheres, the dividing line between the western edge of the solar hemisphere and the night hemisphere is the morning line (Figure 2AB), and the dividing line between the eastern edge of the solar hemisphere and the night hemisphere is the dark line (Figure 3AB). That is, the left night is morning (morning line) and the right night is faint (faint line).
The twilight zone always divides the earth equally (half day and half night).
(4) The twilight zone is constantly moving.
⑤ At any time, the termination line is perpendicular to the sunlight.
⑥ The termination line is sandwiched between two parallel lines and tangent to this parallel line. When the two tangent points are 0 point and 12 respectively, the termination line is divided into a day arc and a night arc by the warp coil passing through this tangent point, and their planes are perpendicular to each other, and the sun shines directly on the meridian of the day hemisphere where the tangent point is located.
4. Determine the position of the direct point of the sun
Because of the intersection of yellow and red, the direct point of the sun moves back and forth between the tropic of cancer in a year. Due to the rotation of the earth, during the day, the sun shines directly on all points on a latitude line between the tropic of cancer and the tropic of cancer. But at a certain moment, it only points directly to one point. There is a rule to determine the direct point: the line connecting the direct light from the center of the sun to the center of the earth or from the center of the sun to the center of the earth is direct light, and its intersection with the earth's surface is direct point. In short, the direct point of the sun is always on the ecliptic plane.
① Determine the latitude of the direct point: in the sunshine map, the morning and evening circles must be tangent to a latitude, so the latitude of the tangent point and the latitude of the direct point of the sun are complementary in value. That is, if the latitude of the direct point is α, the latitude of these two parallel lines is 90-α. From this, we can judge the latitude of the direct point of the sun. As for the south latitude or the north latitude, we can judge it according to the length of day and night. On the side view, the latitude of the sun's direct point is the latitude at which the sun's rays pass through the center of the earth and intersect with the surface of the earth.
② Determine the longitude of the direct point: on the sunshine map, the longitude of the direct point of the sun is the longitude of the meridian bisecting the solar hemisphere. On the side view, the outermost meridian in the daytime hemisphere is the meridian of direct sunlight, and its longitude is the longitude of direct sunlight. In the top view, the meridian is a radial straight line and the latitude is a concentric circle. The longitude of the meridian parallel to or coincident with the sun rays in the daytime hemisphere is the longitude of the direct point of the sun.
③ The pressure zone and wind zone move north and south with the direction.
④ In the area between the Tropic of Cancer, there is direct sunlight twice a year; In the area on the regression line, the sun shines directly once a year.
5. When determining the location.
(1) The point where the morning line intersects the equator on the meridian is 6 o'clock, and the point where the dark line intersects the equator on the meridian is 18 hours. That is to say, at any time, the equator is at 6:00 am and the faint line 18:00.
② The direct point of the sun is 12 when it is located on the meridian, and 0 when it is located on another meridian opposite to noon. That is, when the local time difference between two opposite meridians is 12.
③ longitude difference 15, time difference 1 hour; Longitude difference 1, time difference of 4 minutes (east plus west minus, east early and west late).
④ The longitude is the same and the local time is the same; Different longitudes, different local time.
⑤ On the sunshine chart, the meridian bisecting the day hemisphere is at noon 12:00, and the meridian bisecting the night hemisphere is at 0:00.
⑥ The place where the time zone is consistent with the local time is on the central meridian of each time zone (central meridian degree = 15× time zone number).
⑦ The date will change when crossing the date line. The time on both sides of the date line is the same, but the date is different.
Determine the season
① According to the judgment of the terminator line, the terminator line is a straight line (coincident with the warp coil), which passes through the north and south poles, so it is a bisector; If the termination line is a straight line (side view) or an arc (top view) and both are tangent to the polar circle, it is two solstice days. For example, the Arctic Circle is the summer solstice and the Antarctic Circle is the winter solstice.
② Judging from straight latitude: straight equator, bisector; Capricorn is the second solstice (Capricorn is the summer solstice, Capricorn is the winter solstice).
(3) the northern and southern hemispheres, the same date, the opposite season.
7. Determine the length of day and night
The terminator line divides the latitude of the earth into two parts: day arc and night arc. The length of solar arc and night arc determines the length of day and night. The arc length is 15, that is, 1 hour. On the illumination map, longitude divides latitude into line segments, and the longitude difference between adjacent meridians is generally 30 or 45, indicating that the time difference between each longitude segment is 2 hours or 3 hours. The length of a day or a night can be obtained by reading the Bible.
(1) which hemisphere the sun shines directly on, the day is long and the night is short. The higher the latitude, the longer the day and the shorter the night. In which hemisphere (south or north) does the direct point move? The day becomes longer and the night becomes shorter.
(2) The terminator line coincides with the meridian plane, and the whole world is equally divided day and night; The angle between the end line and the meridian plane is the largest (23 26'), and the difference between day and night is the largest.
③ Determine the length of day and night by looking at the corresponding length of day arc and night arc in the same latitude circle:
④ When the sunrise is known as A, the day length is 2× (12-a), the night length is 2a, and a+b is 24 hours.
When the sunset is known as B, the day length is 2 (A- 12) and the night length is 48-2a.
Day length = sunset-sunrise, night length = 24 days long.
⑤ Different areas at the same latitude have the same length of day and night.
⑥ The sum of day length and night length of two latitudes with equal latitude value is 24 hours, and the relative value of day and night is equal when the sum of night length is 24 hours (the night length of a latitude in the southern hemisphere is equal to the day length of the northern hemisphere with the same latitude value).
8. Determine the time of the sun (sunrise and sunset)
The sunrise time of a place is the moment when the latitude and the dawn line intersect; Sunset time is the intersection of latitude and dark line at this point.
(1) vernal equinox, the sun points directly at the equator, and the termination line bisects all latitudes and is perpendicular to them. So only these two days have the same sunrise and sunset time, that is, 6 o'clock and sunset 18 o'clock.
② Sunrise at 6 o'clock and sunset at 18 o'clock all the year round on the equator.
(3) During the extreme day and night in the polar circle, the sun is always above or below the horizon, so there is no sunrise or sunset.
(4) Sunrise at the same time on the morning line and sunset at the same time on the faint line.
⑤ Calculate sunrise a and sunset b according to the length of day and night:
A = 12- day length =0+ night length B= 12+ day length = 24- night length.
⑥ In areas with the same latitude value, the sunrise and sunset times are the same.
9. Determine the height of the sun at noon
At noon, the height of the sun, the direct point is 90, and the height of the sun gradually decreases from south to north at noon.
(1) The height of the sun at the finish line is always zero. The sun height at the direct point is 90, the sun height in the hemisphere during the day is greater than 0, and the sun height in the hemisphere at night is less than 0.
(2) if the geographical latitude is the same, the noon sun height is the same.
③ The range of noon sun height angle is 0 ≤ h ≤ 90.
④ The noon sun height of each place is equal to 90 minus the difference between the geographical latitude of the place and the geographical latitude of the direct solar point [h = 90-| δ|, (,δ is a positive value, h is the noon sun height angle, δ is the latitude of the direct solar point, and it is "-"when it is in the same hemisphere, and "+"or h = 90- when it is in different hemispheres.
⑤ Calculation of the isocenter between the solar altitude angle and the geographical latitude: in the hemisphere where the direct point of the sun is located, the isocenter is half of the sum of the latitude of the direct point and 90; The latitude of the other hemisphere bisector is half of the absolute value of the difference between the latitude of the direct point and 90.
⑥ At the same time, the difference in sun height between two points on the earth is equal to the difference in latitude between the two points.
10. Find the ratio between today and yesterday on the earth.
On the earth, there are two dividing lines separating the dates * * * One is the artificial national international international date line (longitude180); One is the longitude of 0 or 24 o'clock (not to be confused with the longitude of 0 o'clock). The longitude of 180 is permanently fixed in the world, and the longitude of 0 local time is always changing as the earth rotates from east to west.
① When longitude 0 is 0: 00 (when longitude 0 coincides with longitude 0), longitude 180 is 12: 00, which is exactly two dates in the world.
② When the longitude of 0 at noon is 12: 00, the longitude of 180 is 0: 00 or 24: 00 (0 longitude coincides with180), so there is only one date in the world.
③ When the meridian at 0 o'clock is in the east longitude belt, the new day accounts for less than half of the world, and the previous day accounts for more than half.
④ When the meridian at 0 o'clock is in the western meridian, the new day accounts for more than half, and the previous day accounts for less than half of the world.
⑤ On the sunshine chart, the natural change line increases by one day along the earth's rotation direction, and the international international date line decreases by one day.
6. The date east of the date line is one day less than the date west of the date line, and the date east of meridian 0 is one day more than the date west of meridian 0.
⑦ According to the zone (X) of East 12, the global scale of the new day is x/24. According to the area (y) of the west 12 area, it is enough to calculate the global proportion of the old days, that is, y/24 (when x+y = 24).