1. What is a Graticule?
- The graticule is a network of latitude and longitude lines on the globe or a map.
- It helps us find the exact location of any place on Earth.
- A location is described using one latitude and one longitude.
2. How to Describe the Location of a Place?
- To find the location of a city, country, or region, we use latitudes and longitudes.
- Example: Delhi is located at 28° 36′ 50” N latitude and 77° 12′ 3” E longitude.
- Every place has a unique latitude and longitude.
3. How to Describe the Extent of a Region?
- The extent of a country or region is given using:
- Two latitudes (northernmost and southernmost points).
- Two longitudes (easternmost and westernmost points).
Example:
- Australia’s extent: 10°30′ S to 43°39′ S latitude, 113° E to 153° E longitude.
4. How to Describe the Extent of a Road, River, or Linear Feature?
- The extent of a road or river is described by giving:
- Latitude and longitude of the starting point.
- Latitude and longitude of the ending point.
Example:
- River Nile in Africa:
- Starts at Lake Victoria (0° 45′ 21” S, 33° 26′ 18” E).
- Ends at Mediterranean Sea near Alexandria (31° 12′ N, 29° 55′ 07” E).
- River Nile in Africa:
5. Important Parallels of Latitude
- Parallels are imaginary horizontal lines on Earth.
- Important parallels:
- Equator (0° latitude) → Divides Earth into Northern and Southern Hemispheres.
- Tropic of Cancer (23.5° N) → Northern limit of the sun’s perpendicular rays.
- Tropic of Capricorn (23.5° S) → Southern limit of the sun’s perpendicular rays.
- Arctic Circle (66.5° N) → Beyond this, the sun is visible for 24 hours in summer.
- Antarctic Circle (66.5° S) → Beyond this, the sun is visible for 24 hours in summer.
- North Pole (90° N) & South Pole (90° S) → The extreme ends of the Earth.
6. Important Meridians of Longitude
- Meridians are imaginary vertical lines on Earth.
- Important meridians:
- Prime Meridian (0° longitude) → Divides Earth into Eastern and Western Hemispheres.
- 180° Meridian (International Date Line) → Opposite the Prime Meridian, changes the date when crossed.
- Other meridians: 90° E, 90° W, 45° E, 45° W, 135° E, 135° W.
7. Time and the Prime Meridian
- The Prime Meridian (0° longitude) is used to measure time worldwide.
- The time at this meridian is called Greenwich Mean Time (GMT).
- Countries have different time zones based on their longitude.
8. Why is the Graticule Important?
- It helps to find locations using latitudes and longitudes.
- It is used in navigation, GPS, and map reading.
- It helps in dividing the Earth into climate zones.
- It helps in understanding day and night durations in different regions.
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