What are Latitude and Longitude?

Latitude and longitude is a coordinate system consisting of longitude and latitude. It is called a geographic coordinate system. It is a spherical coordinate system that uses the spherical surface of three degrees to define space on the earth. It can mark any position on the earth.

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The latitude and the meridian are the auxiliary lines hypothesized by humans for the convenience of measurement, and are defined as the trajectory formed by a point on the earth's surface as the earth rotates. Each weft is circular and parallel to each other. The length of the latitude is the perimeter of the equator multiplied by the cosine of the latitude's latitude, so the equator is the longest. The latitude that is farther from the equator, the shorter the perimeter, and it shrinks to zero at the poles. From the equator to the north and south, each at 90 °, is called north latitude and south latitude, and is represented by "N" and "S", respectively.

The meridian is also called the meridian. Like the latitude, it is artificial for the convenience of measurement.

East longitude is positive, west longitude is negative. Longitude is the number of degrees east or west of a location on the earth from a north-south line called the prime meridian. The longitude of the prime meridian is 0 °, and the longitude of other places on the earth is eastward to 180 ° or westward to 180 °. Unlike the latitude, which has the equator as the natural starting point, the longitude has no natural starting point. The line that is the prime meridian is chosen by people. British cartographers use the meridian passing the London Greenwich Observatory as a starting point. In the past, other countries or people have also used other meridians as a starting point, such as Rome, Copenhagen, Jerusalem, St. Petersburg, Pisa, Paris, and Philadelphia. At the International Prime Meridian Conference of 1884, the meridian of Greenwich was officially set as the starting point of longitude. East longitude 180 °, west longitude 180 °, is equivalent to the international day-changing line. The two sides of the international day-changing line differ by one day.

Longitude refers to the dihedral angle formed by the meridian plane passing through a place and the prime meridian plane. Longitude east of the prime meridian is called east longitude, and west of the prime meridian is called west longitude. East longitude is represented by "E" and west longitude is represented by "W".

Each degree of longitude is divided into 60 minutes, and each minute is divided into 60 seconds. A longitude therefore generally looks like this: 23 ° 27 '30 "east longitude or 23 ° 27' 30" west longitude. In more precise longitude positions, seconds are expressed as decimal fractions, such as: 23 ° 27.500 east longitude, but there are also degrees and their decimals: 23.45833 ° east longitude. The West Longitude is sometimes written as a negative number: -23.45833 °. But occasionally someone writes the longitude as a negative number, but this is quite unconventional.

A longitude and a latitude together determine the precise location of a location on Earth.

Each degree of longitude on the equator is about 111km, and the distance of each degree of longitude varies from 0km to 111km. Its distance varies with latitude, which is equal to the cosine of 111km times latitude. However, this distance is not the shortest distance between two points separated by a longitude. The shortest distance is the distance of the arc connecting the two circles, which is smaller than the distance calculated above.

The longitude of a place generally corresponds to the time difference between UTC: 24 hours a day, and 360 degrees in a circle, so the earth rotates 15 degrees per hour. So if a person's place is 3 hours earlier than Coordinated Universal Time, then he is about 45 degrees east longitude. However, because the division of time zones also has political factors in it, a person's time zone may not match the calculation above. But by measuring the time of a place, a person can calculate the longitude of his place. To calculate this data, he needs a clock indicating the coordinated universal time and needs to observe the time when the sun passes through the meridian circle.

Altitude refers to the difference between the height of a place and the sea level, and is the current standard for measuring a place.

North latitude is positive and south latitude is negative.

Latitude refers to a point on the ellipsoid plane as the normal. The angle between the normal of the point and the equatorial plane is between 0 and 90 degrees. The latitude of a point located north of the equator is called north latitude, and it is called N; the latitude of a point located south of the equator is called south latitude, and it is called S.

Areas with latitude values between 0 and 30 degrees are called low latitude areas; areas with latitude values between 30 and 60 degrees are called middle latitude areas; areas with latitude values between 60 and 90 degrees are called high latitude areas .

The equator, the Tropic of Cancer, the Tropic of Cancer, the Antarctic Circle and the Arctic Circle are special parallels.

Cities and other geographic areas near latitudes 90 degrees north: North Pole

80 degrees north latitude:

70 degrees north latitude: Murmansk

60 degrees north latitude: Oslo, Stockholm, Helsinki, Saint Petersburg, Reykjavik

50 degrees north latitude: London, Paris, Brussels, Frankfurt, Prague, Krakow, Kiev, Vancouver, Moscow

40 degrees north latitude: Madrid, Istanbul, Ankara, Kashgar, Beijing, Salt Lake City, Denver, Washington, New York

35 degrees north latitude: Tokyo

30 degrees north latitude: Cairo, Suez Canal, Kuwait City, New Delhi, Everest, Lhasa, Three Rivers, Chongqing, Three Gorges of the Yangtze River, Wuhan, Hangzhou, Houston, New Orleans

20 degrees north latitude: Hong Kong, Sahara, Jeddah, Taiwan, Mumbai, Naypyidaw, Guangzhou, Haikou, Fujian Province, Honolulu, Mexico City

10 degrees north latitude: Mexico City, Conakry, Addis Ababa, Ho Chi Minh City, Cebu, San Jose, Panama City, Panama Canal, Caracas

Equator: Sao Tome, Libreville, Kampala, Singapore, Quito

10 degrees south latitude: Luanda, Dili, Port Moresby, Lima, Recife

20 degrees south latitude: Antananarivo, Suva, Sucre

30 degrees south latitude: Sydney, Cape Town, Bloemfontein, Durban, Brisbane, Easter Island, San Diego

35 degrees south latitude: Canberra

40 degrees south latitude: Wellington

50 degrees south latitude: Strait of Magellan

60 degrees south latitude: Drake Channel

70 degrees south latitude: unknown

80 degrees south latitude: unknown

90 degrees south latitude: Antarctica, Amundsen-Scott Station

Latitude and longitude are expressed in degrees, which can usually be directly expressed as decimal points, but the decimal point of degrees can also be divided into angular points (one angular point equals one-sixth of a degree) and seconds (one second equals one-sixth of a degree). There are various patterns for latitude and longitude, here are some examples.

1. Degrees, minutes and seconds (degrees: minutes: seconds)-49 ° 30'00 "-49d30m00s

2. Degree points (degrees: minutes)-49 ° 30.0'-49d30.0m

3. Degrees indicate -49.5000 ° -49.5000d (usually there will be four decimal places).

Many software can convert different latitude and longitude representation.

In 120 AD, a young man also studied astronomy and geography in this ancient library. He was Crodis Ptolemy. Ptolemy synthesizes the research results of predecessors, and believes that the map should be based on fixed points of known latitude and longitude, and puts forward the concept of drawing a network of latitude and longitude lines on the map. To this end, Ptolemy measured the latitudes and longitudes of important cities and strongholds in the Mediterranean area, and wrote eight volumes of geological works. These include the latitude and longitude of 8,000 places. In order to draw the longitude and latitude lines on the plane, he managed to draw the longitude and latitude lines into a simple fan shape, thereby drawing a famous "Ptolemy map". In the early 15th century, the navigator Henry began to put the "Ptolemy Map" into practice. However, after repeated inspections, it was found that this map was not practical. Some captains of Henry said with regret: "Although we respect the famous Ptolemy, we find that the facts are contrary to what he said."

To accurately determine latitude and longitude, the key is to have a "standard clock". Making accurate timepieces for timing at sea is obviously more convenient and practical than relying on celestial timing. The advancement of mechanical technology in the 18th century has finally created the conditions for solving this long-standing problem. There is a watchmaker Harrison in Yorkshire, England. In 42 years, he has made 5 consecutive timepieces. One is more precise and perfect than the other, and the accuracy is getting higher and higher. The fifth is the size of a pocket watch, and the error caused by measuring longitude is only 1/3 mile. At about the same time, a marine timepiece designed and manufactured by French clockmaker Pierre Leroy was also put into use. At this point, the problem of measuring longitude at sea has finally been initially resolved.

Both longitude and latitude are angles. Longitude is a dihedral angle and is the angle between the two meridian planes. Because all meridians are the same length, in order to measure longitude, a starting point was selected. After an international conference in 1884, it was decided to pass the main meridian crosshair of the Royal Greenwich Observatory (former site) of the Royal Observatory on the South Bank of the Thames in the United Kingdom. The meridian is the starting meridian and is called the prime meridian. The prime meridian plane is the starting plane and the ending plane is the local meridian plane. The longitude of a point is the angle between the meridian plane of the point and the prime meridian plane. Measured on the equator, measured from the original meridian plane as the starting plane, measured eastward and westward respectively. The eastward magnitude is called the east longitude, and the westward magnitude is called the west longitude. It can be seen that the longitude of a place is the direction and angular distance of the place to the prime meridian. The prime meridian is 0 ° longitude, the maximum value of east longitude is 180 °, the maximum value of west longitude is 180 °, and the longitudes of 180 ° east and west are the same meridian. Therefore, there is no distinction between east and west longitudes, and they are collectively referred to as 180 ° warp. (Latitude and longitude) On the globe, what is parallel to the equator is latitude and what is perpendicular to the equator is longitude

The starting plane is the equatorial plane and the line is the local ground normal. The so-called normal is the line perpendicular to the surface of the reference oblate. The latitude of a place is the angle between the normal of the place and the equatorial plane. Latitude is measured on the local meridian, measured from the equator to the south and north. The northward magnitude is called north latitude, and the southward magnitude is called south latitude. It can be seen that the latitude of a place is the direction and angular distance of the place to the equator. The equator is the 0 ° latitude, with a maximum of 90 ° at the north latitude, which is the north pole, and a maximum of 90 ° at the south latitude, the south pole.

On the globe, the longitude and latitude network is composed of the longitude and latitude lines; if the longitude and latitude network globe is expanded, a flat map is formed. Position determination has a role in aviation, aerospace, navigation, and meteorology. "How to rescue a ship when it is in danger at sea", etc., all use the Jingwei map. Longitude: In order to distinguish each meridian on the earth, people have marked the meridian with a degree, this is the longitude. One time zone for every 15 degrees of longitude. In fact, longitude is the angle between the planes where the two meridians lie. Internationally, the meridian passing through the original site of the Greenwich Observatory in London, the capital of the United Kingdom, is designated as a 0 ° meridian, also known as the prime meridian. Starting from the 0 ° meridian, it is divided into 180 ° to the east and west. 180 ° to the east belongs to the east longitude. It is customary to use E as a code, and 180 ° to the west belongs to the west longitude. Code. The east longitude 180 ° and the west longitude 180 ° coincide on a meridian, that is, the east and west 180 ° meridian. Latitude: North latitude (N) is measured from the equator to the north; south latitude (S) is measured to the south. When interpreting longitude on the map, you should pay attention to: from west to east, the longitude of the longitude is from east to longitude; from west to east, the longitude of the longitude is from west to east, the longitude is west; except for 0 ° and 180 ° Longitudes can accurately distinguish between east longitude and west longitude.

longitude

Longitude is divided into 360 degrees, one time zone every 15 degrees, and the first meridian at 0 degrees is the first place to enter the new day, and then one hour to the west every time zone. For example, at 5 am, then one time zone to the west is 4 am, and another time zone is 3 am, and so on, and the opposite is to the east, all the way to the prime meridian, which means that the two sides of the prime meridian are just right 23 hours difference

From the equator to two levels, the latitude is getting higher and higher. The equator is the dividing line between the northern and southern hemispheres

Latitude and longitude 1 degree = 60 minutes = 3600 seconds, this sixty decimal is custom made by the Babylonians, we are still using it today, as long as the angle and circle are the same.

latitude

The latitude of the equator is 0 °, which divides the planet into the southern hemisphere and the northern hemisphere.

Latitude refers to the line plane angle formed by the connection between a point and the center of the earth's sphere and the earth's equatorial plane, and its value is between 0 and 90 degrees. The latitude of a point located north of the equator is called north latitude, and it is called N, and the latitude of a point located south of the equator is called south latitude, and it is called S.

Areas with latitude values between 0 and 30 degrees are called low latitudes, areas with latitude values between 30 and 60 degrees are called middle latitudes, and areas with latitude values between 60 and 90 degrees are called high latitudes. .

The equator, the Tropic of Cancer, the Tropic of Cancer, the Antarctic Circle and the Arctic Circle are special parallels.

1 second of latitude

The total length of the meridian of the earth is about 40008km. average:

1 degree of latitude = about 111km

1 latitude = about 1.85km

Latitude 1 second = about 30.8m

At any location on the earth, as long as there is a watch, a bamboo pole, and a tape measure, you can know the local latitude and longitude. But the table must be proofread against the country standard time.

The method is as follows: 1. Calculate two minutes first

For example, in a certain place in China, the shortest time is 13:20 noon, and the ratio of the length of the pole to the length of the pole is 1, you can know that the place is 45 ° north latitude (tg = 1), 100 ° east longitude (from 120 ° 1 hour minus 15 °, 4 minutes minus 1 °) The ratio of pole length to shadow length needs to look up the table to find . Here, a special angle is used.

2. Calculate the two-to-sun longitude algorithm. The latitude is constant at the northern hemisphere winter solstice + 23.5 °, and the summer solstice -23.5 °.

3. Correction value algorithm: It is the difference between the number of days from two minutes or two to the day multiplied by 94/365. For example, on February 17, 2013, March 22, 2013, the spring equinox was 33 days apart, that is, the direct solar point is at south latitude

33 × 94/365 = 8.5 °

So the latitude obtained at noon today is (arctg + 8.5) °

tg = rod length / shadow length

Due to the difference in ground level and the irregular shape of the earth, astrometric information (such as satellite navigation systems) is not enough to explicitly calculate the geographical location. Here is a more detailed latitude and longitude system:

• WGS84, used by the US Global Positioning System

• GRS80

WGS84, used by the US Global Positioning System.

GRS80

Northern Hemisphere

Bering Strait (170 W, Arctic Circle)

Malacca in Southeast Asia (100 east longitude, 2.2 degrees north latitude)

Strait of Hormuz (Western Longitude 60, Tropic of Cancer)

Mander Strait (45 east longitude, 14 north latitude)

Turkish Strait (East Longitude 30, North Latitude 40)

Gibraltar Strait (5 W, 36 N)

Southern Hemisphere

Mozambique Strait in Africa (Longitude 40, Latitude 20)

Magellan Strait in South America (70 W, 53 S)

Important Peninsula:

Korean Peninsula (126 longitude, 38 latitude)

Indochina Peninsula (100 east longitude, 15 north latitude)

Malay Peninsula (Longitude 102, Latitude 5)

Indian Peninsula (East Longitude 80, North Latitude 20)

Arabian Peninsula (50 East, 20 North)

Sinai Peninsula (35 east longitude, 30 north latitude)

Asia Minor Peninsula (East Longitude 30, North Latitude 40)

Balkan Peninsula (20 east longitude, 40 north latitude)

Apennine Peninsula (East Longitude 15, North Latitude 40)

Iberian Peninsula (5 West Longitude, 40 North Latitude)

Jutland Peninsula (5 east longitude, 55 north latitude)

Skankan Navia Peninsula (10 east longitude, 60 north latitude)

Cape York (145 east longitude, 15 latitude south)

Alaska Peninsula (165 W, 60 N)

Baja California Peninsula (West Longitude 110, Tropic of Cancer)