Latitudes and longitudes form a grid of imaginary lines that help locate any point on Earth. Longitudes are also used to measure time across the world. These concepts appear often in geography and map-based exam questions.
Latitudes
- Latitudes are lines drawn parallel to the Equator.
- The Equator is the longest latitude at 0 degrees.
- There are 181 latitudes in total, including the Equator.
- Important ones are the Tropic of Cancer, Tropic of Capricorn and the polar circles.
Longitudes
- Longitudes run from the North Pole to the South Pole.
- The Prime Meridian at 0 degrees passes through Greenwich.
- There are 360 longitudes in total.
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Time and Longitudes
- The Earth rotates 15 degrees per hour.
- Each 1 degree of longitude equals 4 minutes of time.
- GMT is the time at the Prime Meridian.
Indian Standard Time
- IST is based on the longitude 82.5 degrees East.
- This line passes near Mirzapur in Uttar Pradesh.
- IST is 5 hours 30 minutes ahead of GMT.
Quick Revision Points
- The Equator is the longest latitude at 0 degrees.
- The Prime Meridian passes through Greenwich.
- There are 181 latitudes and 360 longitudes.
- The Earth rotates 15 degrees per hour.
- One degree of longitude equals 4 minutes.
- IST is based on 82.5 degrees East.
- IST is 5 hours 30 minutes ahead of GMT.