How does geography and astronomy judge the southeast and northwest?

First of all, the sun is the most reliable compass.

We know that the sun moves from east to west, while the shadow moves from west to east. For example, at 6 o'clock in the morning, the sun rises in the east, and the shadows of all objects fall to the west; By noon 12, the sun is due south and the shadow points to the north; By 6 pm, the sun is due to the west and the shadow points to the east. So the direction can be roughly determined by the shadows of the sun and objects. As the saying goes: "immediate", use a pole (straight pole) to make it perpendicular to the ground, and put a stone at the vertex A of the pole shadow; About 10 minutes, when the vertex of the column shadow moves to B, put another stone to connect the two points A and B into a straight line. This straight line points to the east-west direction, and the direction perpendicular to the AB line is the north-south direction. The end facing the sun is the south, and the opposite direction is the north.

According to this method to determine the direction, the higher, thinner and more vertical to the ground, the longer the shadow moves, the more accurate the direction will be. Especially around noon 12. For example, the shadow lengths of 1 1: 30 and 12: 30 are almost equal, and the connecting line of vertices just points to the east-west direction, and the vertical line of the connecting line can also accurately point out the north-south direction.

The earth rotates 360 degrees in 24 hours, 1 hour rotation 15 degrees, and the hour hand of a watch is always twice as fast as the sun. According to this principle, the position can be roughly determined by the watch and the sun. At 6 o'clock in the morning, the sun is in the east and the shadow points to the west. At this time, the hour hand on the watch points to the sun, and the word "12" on the dial points to the west. If the dial is rotated by 90 degrees, the 6 o'clock position is half, so that the "3" on the dial faces the sun and the "12" points to the north. At noon, 12, the sun is in the south. If 12 is folded in half so that the "6" on the dial faces the sun, the word "12" still refers to the north.

According to this method, the local time difference should be considered. Time conversion should be set to local time. Take east longitude 120 degrees as the line, east longitude 15 degrees, Beijing time plus 1 hour, west longitude 15 degrees, and Beijing time minus 1 hour as the local time. If the geographical coordinate of Urumqi is 87 degrees 40 minutes east longitude, then (120-87) ÷ 15 = 2 hours and 9 minutes, Beijing time minus 2 hours and 9 minutes, it is the local time in Urumqi.

Taiwan Province Chiayi, Nan 'ao Island, Guangdong Shantou Northeast, Guangxi Wuzhou, Yunnan Gejiu South of the Tropic of Cancer (23 degrees 27 minutes north latitude) can not use the above two methods in summer.

By the way, we know that the relative position of the earth and the sun has moved 15 during the rotation of the earth, and we can roughly determine the direction with the watch and the sun. On the contrary, we can also use the compass and the sun to measure the approximate time. The method is to point to the north with a compass, and the reading of the sun position can be divided by 15. China is based on Beijing time, Beijing is on the east longitude 120 line, and other areas should be corrected according to the longitude difference, that is, the correct solar time.

As the saying goes, "Everything grows on the sun", and the heat energy of the sun has formed many characteristics of indirect direction judgment in nature. After mastering these characteristics, even on a cloudy day without the sun, you can still judge the direction accordingly. For example, the grass in the south near stumps, trunks and boulders grows tall and lush, and the grass in the south withers and turns yellow faster in winter. Bark is generally smooth in the south and rough in the north (there are many cracks and uneven bumps on the bark). This phenomenon is most obvious in birch trees. The bark of birch in the south is lighter and more elastic than that in the north.

In summer, the gum from the trunk of pine, cypress and fir trees is more in the south than in the north, and it is caked. The secondary bark covering the trunk of pine trees formed earlier in the north than in the south and developed higher upward. This phenomenon is more prominent when the bark swells and turns black after rain. In autumn, the south-facing side of fruit trees has dense branches and leaves and many fruits, especially apples, red dates, persimmons, hawthorn, lychee and citrus. When the fruit is ripe, it is dyed to the south side first.

Ant nests near trees and shrubs are always in the south of trees and shrubs.

Moss growing on stones likes humidity and is not resistant to sunlight, so mosses generally grow on the north side of stones.

The leaves of Mongolian chrysanthemum and wild lettuce on the grassland point north and south.

In the mountainous and hilly areas of northern China, dense arbor forests mostly grow on shady slopes, while shrub forests mostly grow on sunny slopes. This is due to the slow evaporation of water on shady slopes and good soil and water conservation, so vegetation restoration is faster than that on sunny slopes, and it is easy to form forests. Judging from the tree habits, fir and spruce grow well on the northern slope, while Pinus massoniana, Pinus armandii, birch and poplar grow mostly on the southern slope.

In spring, the first side of snow melts facing south and the second side melts facing north. In deep pits and depressions, the snow in the north melts earlier in the sun. Most rivers in the permafrost regions in the north are gentle in the north and steep in the south.

In addition, most temples, pagodas and general houses face south. The gate of the Islamic mosque faces east (west). Polaris is usually used to determine direction at night. Looking for Polaris, we must first find Ursa Major (commonly known as the Big Dipper), because it always keeps a certain position relationship with Polaris and keeps spinning. After the Big Dipper was found, it extended to the spoon mouth along the connecting line of two stars A and B on the spoon side, which was about five times the distance between the two stars A and B, and there was a brighter star, namely Polaris. In the area south of 40 degrees north latitude, the Big Dipper often rotates below the horizon, especially at dusk in winter, which is often invisible. At this time, we should look for the North Star according to the Hou Xian constellation opposite the Big Dipper. Hou Xian constellation consists of five stars with brightness similar to that of the Big Dipper, forming a "W" shape. In front of the middle of the W-shaped gap, about twice the width of the whole gap, you can find the Polaris.

In the area south of 23 degrees north latitude, you can use the Southern Cross to determine the direction of the first half of the year. The Southern Cross is mainly composed of four bright stars connected diagonally to form a cross. It extends downward along the connecting line between two stars A and B, and it is located due south, which is about four and a half times the distance between the two stars.

You can also use the moon to determine the direction at night. The moon rises and sets regularly. The moon rises 48-50 minutes later than the previous day. For example, on the fifteenth day of the lunar calendar 18, the moon rises in the east. On the twentieth day of the lunar calendar, the distance is 5 days, it rises about 4 hours later and appears in the eastern sky at about 22: 00. The phase change of the "full moon" is also regular. Before the fifteenth lunar month, the bright part of the moon is on the right, and after the fifteenth, the bright part of the moon is on the left. The first half of the month is the first quarter moon, the middle of the month is the full moon, and the second half is the second quarter moon. Every month, the moon rises and falls according to the above two laws. Please refer to the table below to determine the orientation by using the moon.

In addition, according to the law of the moon's rotation from east to west, it takes about 12 hours, with an average rotation of about 15 degrees. Combined with the moon phase, position and observation time at that time, the direction can be roughly determined. For example, at night 10, when you see the moon in the night sky on the right side, you can judge that it is the first quarter moon, the sun sets at 6 o'clock and the moon is due south; At this time 10-6: 00 = 4: 00, that is, four hours have passed, and the moon has rotated during this period 15× 4 = 60. Therefore, if the position of the moon is deflected 60 degrees to the left (east) at this time, it is due south. In nature, the wind can also help us know the direction. Such as wooden pillars, the windward side is dark and perishable, while the windward side of cliffs and stones is smooth. But you must be familiar with the prevailing local wind direction, which is especially important in desert areas.

Wind is an important factor in shaping the surface morphology of desert land, and crescent dunes and dune chains are generally dominant in a single wind direction area. The windward slope of sand dunes and ridges is gentle; Leeward side with steep slope. In the northwest, due to the prevailing northwest wind, sand dunes generally form from northwest to southeast. The northwest slope of sand dunes is small and the sand is hard, while the southeast slope is large and the sand is soft. Under the action of northwest wind, plants in desert areas, such as butter grass, red willow, Haloxylon ammodendron and camel thorn, tilt to the southeast. The door of a yurt usually faces the southeast of the leeward side. In winter, many snow ridges and sand ridges are often formed near hay, with a big head and a small tail, and the direction pointed by the head is northwest. These are the general characteristics of desert areas. The wind direction also varies with different regions and seasons. Therefore, judging the direction according to the characteristics of wind direction, we should refer to the local military geography at ordinary times and understand the prevailing wind direction in four seasons in order to get the correct judgment. It should also be noted that pyramid-shaped sand dunes will appear in areas with multiple wind directions and similar winds. It is complicated to determine the direction in this respect, and it is necessary to refer to the comprehensive determination of the sun, moon and stars.

It is worth mentioning that it is well known that "independent trees usually have dense branches and leaves in the south and sparse branches and leaves in the north." "The annual ring of the stump of an independent tree is usually small in the north and small in the south." , but it is actually much more complicated. 1945 m beria Foucault of the former Soviet union pointed out after systematic observation: "You can't judge the direction by the branches and rings of trees. Lush leaves are usually not in the south, but on the other side of free space. As far as independent trees are concerned, besides sunshine, wind and other factors also have great influence, so judging the direction is often unreliable. Similarly, even the annual rings of independent trees are not necessarily wide in the south; It is not only the sun but also the wind that affects the width of the rings. In addition, the width of the annual rings varies vertically, and cutting trees at different heights will get different results. " According to field observation, beria's view is reasonable. For example, the independent trees in Helan Mountain Valley in Ningxia are influenced by perennial winds and westerly winds, and all branches and leaves face east, not south.

When using natural features to determine the orientation, we should pay special attention to the specific analysis of the specific situation and avoid copying it mechanically. When determining the direction, we must pay attention to the comprehensive use of various methods to complement each other and verify each other. China has a vast territory, and the natural conditions in different regions are very different. On the basis of mastering the same laws of * * *, we should also pay attention to the special laws of various regions in order to draw a correct judgment.

Understand?