Latitude, Longitude and Standard Time

📐 Latitude

Imaginary horizontal lines drawn on the globe (East to West)
Angular distance of a place North or South from the Equator
Latitude parallels are parallel; degree spacing is approximately equal and varies slightly with latitude.
Distance represented by 1° latitude ≈111 km on average
Total latitudes – 181 • Latitude lines/circles at the interval of 1° – 179 (excluding the two poles)

📌 Use of Latitude Useful in locating a place and determining climatic zones

📏 Important Latitude Lines

Latitude	Name	Key Feature
0°	Equator	Divides Earth into Northern and Southern hemispheres
23½° N	Tropic of Cancer	Sun is directly overhead on 21 June (Summer Solstice)
23½° S	Tropic of Capricorn	Sun is directly overhead on 22 December (Winter Solstice)
66½° N	Arctic Circle	Approximate southern limit of the Arctic polar-day/polar-night region
66½° S	Antarctic Circle	Approximate northern limit of the Antarctic polar-day/polar-night region
90° N	North Pole	Northern end of Earth's axis
90° S	South Pole	Southern end of Earth's axis

⚡ Quick Recall

1° latitude ≈111 km on average; the exact meridional distance varies slightly with latitude.

🌡️ Temperature Zones

Torrid Zone

Region between Tropic of Cancer and Tropic of Capricorn

Temperate Zone

Region between Tropic of Cancer / Capricorn and the Arctic / Antarctic circles (in respective hemispheres)

Frigid Zone

Region between Arctic Circle and North Pole (Northern Hemisphere) / Region between Antarctic Circle and South Pole (Southern Hemisphere)

⚠ Exam Trap

Torrid Zone lies entirely between the two Tropics — don't confuse it with the Temperate Zone, which lies beyond the Tropics up to the Polar Circles.

🌍 Countries on the Equator (13 Countries)

EcuadorColombiaBrazilSão Tomé and PríncipeDR Congo GabonRep. of the CongoUgandaKenyaSomalia MaldivesIndonesiaKiribati

📌 Oceans crossed Atlantic, Pacific & Indian Ocean

🌍 Countries on Tropic of Cancer (18 Countries)

MexicoBahamasW. SaharaMauritaniaMali AlgeriaNigerLibyaChadEgypt Saudi ArabiaUAEOmanIndiaMyanmar BangladeshChinaTaiwan

🌍 Tropic of Capricorn — 10 Countries on Land

ChileArgentinaParaguayBrazilNamibia BotswanaS. AfricaMozambiqueMadagascarAustralia

⚡ Quick Recall

Brazil is the only country that lies on both the Equator and Tropic of Capricorn.

📍 Longitude

Prime Meridian (0° Longitude) or Greenwich Line – reference for angular distance of any place
Imaginary lines joining North and South Pole
Lines are not parallel
Distance between longitudes increases from poles towards the equator
Minimum distance – at poles • Maximum distance – 111.32 km (at the Equator)
Total Longitudes – 360

📌 Measurement unit Degree, Minute and Second

📌 Distance between two longitude lines Navigation term: Departure, measured along a stated parallel

🇬🇧 Prime Meridian / Greenwich Mean Time

Passes through Greenwich Observatory (London)
Historic Greenwich meridian crosses 8 countries in Europe and Africa; it also continues to Antarctica.

United KingdomFranceSpainAlgeria MaliBurkina FasoTogoGhana

📌 0° Latitude × 0° Longitude intersect In the Atlantic Ocean (Gulf of Guinea)

⚡ Quick Recall

Greenwich-line countries (memory list, not geographic order): UK, France, Spain, Algeria, Mali, Burkina Faso, Togo and Ghana.

🕒 Time Determination / Standard Time

Earth rotates 360° in 24 hours
In 1 hour = 15° (360° ÷ 24 = 15°)
Time taken to rotate 1° = 4 minutes
Increase in time for going east of 0° Longitude
Decrease in time for going west of 0° Longitude
Time difference for 1° longitude: 4 minutes

🇮🇳 India's Standard Time

82½° E

India's Standard Meridian

+5:30

Ahead of GMT

📌 Basis of World's Standard Time Greenwich Mean Time (GMT)

⚠ Exam Trap

India is ahead of GMT by 5 hours 30 minutes (not behind) since 82½°E lies east of the Prime Meridian.

🌐 International Date Line (IDL)

Location: 180° Longitude → Zig-Zag path
One day difference between East and West of the line
Bends through the Bering region to keep Russia and Alaska on different calendar sides.

🔁 Crossing the IDL

Going West (East → West)

Add one calendar day
Date moves forward by one day

Going East (West → East)

Subtract one calendar day
Date moves back by one day

📌 Important Facts

Idealized longitude model: 24 one-hour zones of about 15° each; civil boundaries vary.
France: 12 standard time zones including overseas territories; seasonal DST can yield a 13th local time.
When it is 12 noon on the Greenwich meridian, sunrise (local 6 AM) occurs at 90° West longitude

⚡ Quick Recall

Mnemonic: "FEST" — IDL zig-zags to avoid splitting countries, especially around Russia/Alaska and Pacific island nations.

🌎 Hemispheres

Horizontal Division — by Equator

Northern Hemisphere (0° to 90° North Pole)
Southern Hemisphere (0° to 90° South Pole)

Vertical Division — Prime Meridian & 180° Meridian

Eastern Hemisphere
Western Hemisphere

⚡ Quick Recall

Equator: North/South hemispheres; 0° and 180° meridians: East/West hemispheres. The zig-zag IDL is a calendar boundary.

🧭 LATITUDE, LONGITUDE & STANDARD TIME World Geography · Ch 05

Torrid Zone

Temperate Zone

Frigid Zone

Going West (East → West)

Going East (West → East)

Horizontal Division — by Equator

Vertical Division — Prime Meridian & 180° Meridian