Chapter latitude and logitude
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Locations on Earth are described by their latitude and longitude coordinates. Latitude is the distance north or south of the equator, measured in degrees from 0 degrees at the equator to 90 degrees at the poles. Lines connecting points of equal latitude are called parallels. Longitude is the distance east or west of the Prime Meridian, measured in degrees from 0 degrees at the Prime Meridian to 180 degrees east and west. The Prime Meridian passes through the Greenwich Observatory in England. The rotation of the Earth causes the sun to traverse 15 degrees of longitude per hour, causing time to change by 4 minutes when moving between meridians. The International Date Line approximates the 180th meridian, where the date changes when traveling east or
Chapter latitude and logitude
- 1. Latitude, Longitude and Time
- 2. Our Earth is nearly a sphere. Any location on Earth is described by two numbers its latitude and longitude. If a pilot or a ship’s captain wants to specify position on a map. These are the ‘coordinates’ they would use.
- 3. The GridThe spinning of the Earth on its axis from west to east provides two natural points of reference, i, e, North and South Poles. They form the basis for the geographical grid. A network of intersecting lines is drawn for the purpose of fixing the location of different features. The grid consist of two sets of horizontal and vertical lines, which are called parallels of latitude and the meridians of longitude. North Pole South Pole West East North West South West North East South East Equator Meridian
- 4. Parallels of Latitude The latitude of a place on the Earth’s surface is its distance north or south of the equator, measured along the meridian of that place as an angle from the centre of the earth. Lines joining places with the same latitude are called parallels. The value of equator is o degree and the latitude of the poles are 90N and 90S.
- 5. If parallels of latitude are drawn at an interval of one degree, there will be 89 parallels of latitude in the northern and the southern hemispheres each. The total number of parallels thus draw, including the equator, will be179. Depending upon the location of a feature of a place north or south of the equator, the letter N or S is written along with the value of the latitude.
- 6. Meridians of Longitude Unlike the parallels of latitude which are circles, the meridians of longitude are semi circles that converge at the poles. If opposite meridians are taken together, they complete a circle, but, they are valued separately as two meridians
- 7. The meridians intersect the equator a right angles. Unlike the parallels of latitude, they are all equal in length. For convenience of numbering, the meridian of longitude passing through the Greenwich Observatory has been adopted as the Prime Meridian by an international agreement and has been given the value of o degree
- 8. The longitude of a place is its angular distance east or west of the Prime Meridian. It is also measured in degrees. The longitudes vary from 0 to 180 degree eastward and westward of the Prime Meridian. The part of the earth east of the Prime Meridian is called the eastern hemisphere and in its west referred to as the western hemisphere.
- 9. Longitude and Time We all know that the earth rotates from west to east over its axis. It makes the sun rise in the east and set in the west. The rotation of the earth over its axis takes 24 hours to complete one circle or 360 degree of longitudes. As 180 degree of longitudes fall both east and west of the Prime Meridian, the Sun, thus takes 12 hours’ time to traverse the eastern and western hemispheres.
- 10. In other words, the sun traverse 15 degree of longitudes per hour or one degree of longitude in every four minutes of time. It may further be noted that the time decreases when we move from west to east and increases with our westward movement.
- 11. International Date Line While the world is divided into 24 time zones, there has to be a place where there is a difference in days, somewhere the day truly ‘starts’ on the planet. The 180 line of longitude is approximately where the International Date Line passes. The time at this longitude is exactly 12 hours from the 0 longitude, irrespective of one travels westward or eastward from the prime meridian.