Geographical Coordinate System Lecture Notes PDF

LECTURE NO. 1 Geograhical Coordinate System Geographical Coordinate System: Latitude and Longitude form a geographical coordinates system that describes a location on Earth. Latitudes: Latitudes are imaginary horizontal lines extended on the globe from the East to West. Latitudes varies from 0o at...

LECTURE NO. 1 Geograhical Coordinate System Geographical Coordinate System: Latitude and Longitude form a geographical coordinates system that describes a location on Earth. Latitudes: Latitudes are imaginary horizontal lines extended on the globe from the East to West. Latitudes varies from 0o at the equator to 900.North (North Pole) and 90° South (South Pole). Latitudes are also known as Parallels. Because parallels never meet and are always equidistant. Get shorter toward the poles, with only the equator, the longest, a great circle. Equator: Line with zero-degree latitude is called Equator. The Equator (0° latitude) divides the Earth into the Northern and Southern Hemispheres. Latitudes play a major role in determining climate zones: Total no. of latitudes is 181, including the equator.  90 latitudes in the Northern Hemisphere (from 1°N to 90°N).  90 latitudes in the Southern Hemisphere (from 1°S to 90°S).  1 latitude for the Equator (0°). ✅ Total = 90 + 90 + 1 = 181 latitudes. The distance between any two consecutive latitudes (1° apart) is approximately 111 km (69 miles). Formula to Calculate Distance: Distance = (π× R/180) × Δθ  R = 6371 km (Earth’s average radius)  Π = 3.1416  Δθ = Difference in latitude (in degrees) For 1° latitude: 3.1416 × 6371 / 180 ≈ 111 km  The distance remains nearly constant because latitude lines are parallel.  Longitude distances vary since meridians converge at the poles. The axial tilt of earth (also called obliquity) is the angle between Earth's rotational axis and its orbital plane around the Sun. Axial Tilt of earth = 23.50 Tropic of Cancer is 23o 26’ 10.5’’ (23.43624 N), while the Tropic of Capricon is 23o 26’10.5’’ (23.43624 S). The word “tropic” comes from a greek term “tropos” which means “turn” or “change”. This refer to the fact that the sun appears to “turn back” when it reaches these latitudes. The Tropic of caner is the northern most latitude where the sun is directly overhead, which occurs on the June solstice (Summer solstice). The Tropic of Capricon is the southernmost latitude where the sun is directly overhead, which occurs on the December solstice (Winter solstice). Earth's orbit around the Sun is elliptical, meaning the distance between Earth and the Sun changes throughout the year.The words come from ancient Greek, in which helios means “Sun,” apo means “far,” and peri means “close.” Aphelion (Farthest from the Sun = 152.1 million km ) – Occur around 3rd -4th July  Earth is at its farthest point to the Sun (~152 million km).  Sun appears slightly smaller in the sky. Perihelion (Closest to the Sun = 147.1 million km) – Around January 3rd  Earth is at its closest point to the Sun (~147 million km).  The Sun appears slightly larger in the sky.  More solar energy reaches Earth, but it does NOT cause summer because seasons are controlled by Earth’s tilt (23.5°), not distance. ❌ Seasons are NOT caused by Earth’s distance from the Sun. ✅ Seasons are controlled by Earth’s axial tilt (23.5°). Summer Solistice (June Solistice): Sun is directly overhead at the Tropic of Cancer (23.5°N). The longest day and shortest night of the year in the Northern Hemisphere. The Northern Hemisphere gets maximum daylight hours..  The Arctic Circle (66.5°N) experiences 24 hours of daylight.  Occurs around June 21st each year. Opposite Effect in the Southern Hemisphere: The countries of Southern Hemisphere experience shortest day & longest night. The Antarctic Circle (66.5°S) experiences 24 hours of darkness (Polar Night). Winter Solistice (December Solistice): Sun is directly overhead at the Tropic of Capricon (23.5°S). The longest day and shortest night of the year in the Southern Hemisphere. The Southern Hemisphere gets maximum daylight hours.  The Antarctic Circle (66.5°N) experiences 24 hours of daylight.  Occurs around December 21st each year. Opposite Effect in the Northern Hemisphere: The countries of Northern Hemisphere experience shortest day & longest night. The Arctic Circle (66.5°S) experiences 24 hours of darkness (Polar Night). Equinox: The Sun is directly overhead at the Equator. Day and night are nearly equal in length all over the Earth. Equinox occurs twice a year.  Spring equinox: Occur 20th - 21st March  Fall equinox: Occur 22nd-23rd September Longitude (Meridians): Longitudes are imaginary vertical lines(semicircles) drawn/extend/run on the globe from the North to South Pole. Longitudes are also called meridians. Prime Meridian: Line with zero-degree longitude is called Prime Meridian. Longitudes varies from 0o at the greenwhich, London to 360O at the midway of pacific ocean. 180° longitude line / meridian is called the International Date Line (IDL), it lies directly opposite to 0° meridian. They help in determining time zones and local time. Total no. of meridians is 3600. The distance between any two meridians is not equal. At the equator, 1o = 111 km At the 30oN and 30oS, 1o = 96.5 km Goes on decreasing this way until it is zero at the poles. International Date line: It is established in 1884, passes through the Mid-Pacific Ocean, roughly follows a 180O. For Example:  East to West (e.g., Japan → United States) → Add a day (Gain a day) If it is Monday in Japan and you travel westward to the United States, it becomes Sunday.  West to East (e.g., United States → Japan) → Lose a day If it is Monday in the United States and you travel eastward to Japan, it becomes Tuesday. Earth doesn’t take 24 hours to rotate on its axis, actually it takes 23 hours, 56 minutes and 4 seconds. Coordinate system most commonly describe in two units. Degree Minute seconds (DMS) Coordinates of Faisalabad Clock Tower Latitude: 31° 25′ 07.22″N Longitude: 73° 04′ 44.90″E a) Convert Degree Minute Seconds (DMS) to Decimals: Latitude: 31° 25′ 07.22″N 31+ 25/60 + 7.22/3600 31 + 0.4166 + 0.00200 31.418 Longitude: 73° 04′ 44.90″E 73+ 04/60 + 44.90/3600 73 + 0.0666 + 0.01247 73.079 b) Convert Decimals to Degree Minute Seconds (DMS): 31.4187 31.4187 x 60 31 25.122 31 25.122 x 60 31 25 7.32 31° 25′ 7.22″