On the map and the globe, you can see thin lines, horizontal and vertical, and some are like square grids on a chessboard. These are the lines of longitude and latitude. According to these latitude and longitude lines, the position and direction of any place on the ground can be accurately determined.
1.1 Latitude and Latitude
How is the line of latitude determined? The earth is constantly rotating around the earth’s axis (the earth’s axis is an imaginary line that passes through the north and south poles of the earth and the center of the earth). At all points equal to the distance between the north and south poles, this circle is called the “equator”. On the north and south sides of the equator, draw many circles parallel to the equator, called “latitude circles”, and the line segments that make up these circles are called latitude lines. The latitude has a total of 90°, that is, 90° to the south and north. The equator is defined as the latitude of zero degrees (0°), and it is arranged to the poles. The smaller the circle, the greater the degree. The latitude of a point located north of the equator is called north latitude, denoted as N, and the latitude of a point located south of the equator is called south latitude, denoted as S. That is, each 90° from south to north, the north pole is 90° north latitude, and the south pole is 90° south latitude. The height of the latitude also marks the hot and cold climate. For example, there is no winter in the equator and low latitudes, no summer in the poles and high latitudes, and the four seasons in the middle latitudes are distinct.
The area with a latitude value between 0 and 30° is called a low latitude area, an area with a latitude value between 30° and 60° is called a mid-latitude area, and an area with a latitude value between 60° and 90° is called high latitude. Latitude area.
Each latitude (and longitude is the same) can be divided into 60′, and each is divided into 60′.
Latitude 1 is approximately equal to 111km.
Latitude 1 is approximately equal to 1.85km
Latitude 1 is approximately equal to 30.9m
Here are just a few examples to show cities and other geographic areas near each latitude line.
90° North Latitude: North Pole
Latitude 40° North: Beijing, Washington, New York, Tokyo, Seoul, Madrid, Istanbul, Ankara, Kashgar.
North latitude 30°: Mount Everest, Lhasa, Chongqing, Three Gorges of the Yangtze River, Wuhan, Hangzhou, Suez Canal, Kuwait City, New Delhi.
Latitude 20° North: Hong Kong, Taiwan, Sahara Desert, Mumbai, Haikou, Honolulu, Mexico City Equator: Singapore, Sao Tome, Libreville, Kampala.
30° south latitude: Sydney, Cape Town, Bloemfontein, Durban, Brisbane, Easter Island, San Diego.
Latitude 40° South: Wellington
Latitude 50° South: Strait of Magellan
90° south latitude: Antarctica
1.2 Longitude and Longitude
From the North Pole to the South Pole, many large circles in the north-south direction and perpendicular to the earth’s equator can be drawn. This is called the “warp circle”; the line segments that make up these circles are called the meridian. It is the line connecting the two poles on the ground, indicating the north-south direction. The meridian is also called the warp. All warp threads are equal in length. Scientists call a meridian (0° longitude) from which the longitude is calculated as the prime meridian. According to international regulations, the line of longitude that passes through the original site of the Greenwich Observatory in London, the capital of the United Kingdom, is set as 0° (the starting point for calculating the longitude, that is, the longitude is zero degrees, zero minutes and zero seconds). The prime meridian is the zero-degree longitude on the earth. It is a standard reference meridian used to determine the longitude of the earth and the global time. It does not have a natural starting point, the equator, like the latitude. The total length of the earth’s meridian is about 40008km.
Each longitude and latitude can also be divided into “minutes” and “seconds”. 1° is equal to 60′, and each minute is equal to 60″. The longitude and the latitude perpendicular to it constitute the coordinates on the earth, that is, the latitude and longitude network. Any one on the earth The location of a place can be represented by the intersection of a line of warp and a line of latitude.
For example, what is the latitude and longitude of Beijing? It can be easily found from the map that it is 116°24 east longitude and 3954′ north latitude. For ships sailing in the sea, as long as the longitude and latitude of the location are measured, the position and direction of the ship in the ocean can be determined.
China has a vast territory, the northernmost point is near the center line of Heilongjiang main channel (53°N latitude) north of Mohe, Heilongjiang Province; the southernmost point is Zengmu Shoal (near 4°N latitude) in the Nansha Islands; the north-south span is about 50°, The distance is 5500km. The easternmost point is at the confluence of the main channel of Heilongjiang and Wusuli River (near 135°E), and the westernmost point is the Pamir Plateau in Xinjiang (near 73°E). The east-west longitude is about 62°, and the distance is more than 5,000 kilometers.
1.3 Twenty-four solar terms
With the continuous movement of the sun and the earth, the solar radiation energy on the earth also changes periodically. People divide the twenty-four solar terms according to the position of the sun on the ecliptic (that is, the orbit of the earth around the sun). Regarding the sun starting from the vernal equinox (zero degrees of the yellow longitude, at this moment the sun illuminates the equator vertically), each advance 15° is a solar term, and it travels a week to return to the vernal equinox, which is a tropical year, which is 360°, so it is divided into 24 solar terms.
It can be seen from the naming of the twenty-four solar terms that the division of solar terms takes full account of the changes in natural phenomena such as seasons, climate, and phenology. Among them, the beginning of spring, beginning of summer, beginning of autumn, beginning of winter, vernal equinox, autumnal equinox, summer solstice, and winter solstice are used to reflect the seasons. The year is divided into four seasons: spring, summer, autumn and winter. The vernal equinox, the autumnal equinox, the summer solstice, and the winter solstice are divided from an astronomical point of view, reflecting the turning point of the sun’s height change, while the beginning of spring and the beginning of summer, the beginning of autumn and the beginning of winter reflect the beginning of the four seasons. Because of China’s vast territory, it has a very obvious monsoon and continental climate, and the weather and climate vary greatly from place to place. Therefore, the seasonal changes in different regions are also very different.