World Geography: Earth, Time, Continents and Oceans
Earth's motions and seasons, latitudes, longitudes and time zones, continents, oceans and world records, straits, the atmosphere and winds, earthquakes, and the country facts exams ask.
Mount Everest, the world's highest peak, seen from the Tibet side. It stands on the Nepal–China border. Its height, re-measured by Nepal and China in 2020, is 8,849 m. Image: Luca Galuzzi (Lucag), Wikimedia Commons · CC BY-SA 2.5
World geography starts with the Earth itself: how it spins and moves round the Sun, and the lines we draw on it to fix places and time. Then come the continents and oceans, the seas and straits between them, the air above, and the rocks below that cause earthquakes. Exams also ask a few country facts.
On this page you will learn:
Rotation, revolution and why we have seasons
Latitudes, longitudes, IST and the International Date Line
Continents, oceans and world records
Seas, straits and canals
Layers of the atmosphere, winds and ocean currents
Plates, earthquakes and volcanoes
Neighbours' languages and currencies
82.5°E
India's standard meridian
IST = GMT + 5:30
7
Continents
Asia biggest, Australia smallest
5
Oceans
Pacific biggest and deepest
Earth's motions and the seasons
Rule in one line: rotation gives day and night; revolution with a tilted axis gives the seasons.
THE TWO MOTIONS
Rotation
Revolution
What it is
Spinning on its axis
Moving round the Sun
Time taken
About 24 hours
365¼ days
Direction
West to east
Elliptical orbit
Result
Day and night
Seasons; leap year
The extra ¼ day adds up to one day in 4 years — that is 29 February in a leap year. The axis is tilted 23½° from the vertical.The axis keeps pointing the same way as the Earth goes round the Sun. In June the northern half leans towards the Sun (summer in the north); in December it leans away. Yellow = northern season, pink = southern season. Image: Tauʻolunga, Wikimedia Commons · CC0
Date
Event
Sun overhead at
21 June
Summer solstice: longest day in the north
Tropic of Cancer
22 December
Winter solstice: shortest day in the north
Tropic of Capricorn
21 March, 23 September
Equinoxes: day = night everywhere
Equator
Textbook dates; in a given year they can shift by a day. The Earth is closest to the Sun in early January and farthest in early July — so distance does not cause our seasons.
QUICK CHECK
PYQ · PPSC ARO 2022 — Given are two statements. Statement I: Angle and intensity of the rays striking any point on Earth change as Earth orbits the Sun. Statement II: The influence of the tilt of Earth's axis overrides the variation associated with seasonal changes in the distance between Earth and the Sun due to Earth's slightly elliptical orbit. Choose the most appropriate answer.
Tap an option to answer
Answer: A — Both Statement I and Statement II are correct
Both are true. The tilt changes how steeply the Sun's rays fall through the year, and that matters far more than the small change in distance.
Latitudes and longitudes
Rule in one line: latitudes run east–west and tell how far north or south; longitudes run pole to pole and tell time.
Left: latitudes (parallels), 0° at the Equator up to 90° at each pole. Right: longitudes (meridians), 0° at the Prime Meridian (Greenwich) up to 180°. All meridians meet at the poles, so the gap between them shrinks towards the poles. Image: Djexplo, Wikimedia Commons · CC0
Line
Latitude
North Pole
90°N
Arctic Circle
66½°N
Tropic of Cancer
23½°N
Equator
0°
Tropic of Capricorn
23½°S
Antarctic Circle
66½°S
South Pole
90°S
Between the two tropics lies the hot (torrid) zone; beyond the polar circles, the cold (frigid) zones.
KEY TERM
Great circle
A circle on the globe whose centre is the centre of the Earth. The shortest route between two places runs along a great circle; that is why long flights curve over the poles on a flat map. The Equator is the only parallel that is a great circle; every pair of opposite meridians makes one.
QUICK FACT
The Tropic of Cancer crosses India through 8 states (Gujarat to Mizoram). Outside India it passes through Bangladesh, Myanmar, China, Oman, the UAE, Saudi Arabia, Egypt, Libya and on to Mexico — but not through Sri Lanka, Afghanistan or the Philippines.
QUICK CHECK
PYQ · PPSC OHE 2016 — As we move towards the Poles, the relative distance between two meridians of longitude
Tap an option to answer
Answer: B — Decrease in a definite proportion
Meridians are widest apart at the Equator and meet at the poles, so the gap shrinks steadily as you go towards either pole.
QUICK CHECK
PYQ · PPSC ICS 2016 — The shortest distance between any two points on the Earth is measured along a
Tap an option to answer
Answer: D — Great Circle
Along a great circle. A loxodrome (rhumb line) keeps one compass direction but is longer.
QUICK CHECK
PYQ · PPSC AEE 2024 — The Tropic of Cancer traverses through which of the following combination of countries?
Tap an option to answer
Answer: C — India, China, Saudi Arabia, Egypt, Libya
All five in option C lie on the Tropic of Cancer. The Philippines and Sri Lanka are south of it; Afghanistan is north of it.
Longitude and time
Rule in one line: 15° of longitude = 1 hour; places to the east are ahead in time.
KEY TERM
Working out IST
The Earth turns 360° in 24 hours: 15° each hour, or 1° every 4 minutes. India's standard meridian is 82°30'E (82.5°E), which passes near Mirzapur in Uttar Pradesh. 82.5 × 4 = 330 minutes, so IST is 5 hours 30 minutes ahead of GMT.
Standard time zones of the world. Each band is about 15° wide. India uses one zone, +5:30. The zig-zag line at the far right and left is the International Date Line. (Country boundaries on this map are not authoritative; India's official map shows all of Jammu & Kashmir and Ladakh as Indian.) Image: UnaitxuGV, Heitordp and others, Wikimedia Commons · Public domain
0°
Prime Meridian
Passes through Greenwich, London. Its time is GMT (now called UTC).
180°
International Date Line
Roughly along 180°, bent to avoid land. Cross it going west: add a day. Going east: go back a day.
Same line
Same longitude
Places on one meridian share the same time and date, however far apart north to south.
A globe has 360 degrees of longitude: 180 east and 180 west of Greenwich.
QUICK CHECK
PYQ · PPSC TM 2015 — The Indian Standard Time (IST) is ahead of GMT by:
PYQ · PPSC TM 2015 — The line just opposite to the Prime Meridian on the globe, that is, the 180 degree longitude is called:
Tap an option to answer
Answer: D — The International Date Line
The International Date Line, roughly along 180°. The Meridian of Greenwich is 0°.
Continents, oceans and world records
Rule in one line: Asia is first in both land and people; Australia is the smallest continent, the Pacific the largest ocean.
Rank
By area
By population
1
Asia
Asia
2
Africa
Africa
3
North America
Europe
4
South America
North America
5
Antarctica
South America
6
Europe
Australia (Oceania)
7
Australia
Antarctica (no permanent people)
The seven continents. The two smallest by area are Australia and Europe. In increasing order of people: North America, Europe, Africa, Asia.
1
Pacific
Largest and deepest; about a third of the Earth's surface. Holds the Mariana Trench.
2
Atlantic
S-shaped; the busiest for sea trade.
3
Indian
The only ocean named after a country. Mauritius and Christmas Island lie in it.
4–5
Southern and Arctic
The Southern Ocean rings Antarctica; the Arctic is the smallest and shallowest.
The five oceans, largest first.
RELIEF OF THE OCEAN FLOOR, FROM THE COAST OUTWARDS
1
Continental shelf
Shallow edge of the land under the sea
↓
2
Continental slope
Steep drop to the deep ocean
↓
3
Deep-sea plain
Flat, wide ocean floor
↓
4
Ocean deeps (trenches)
The deepest parts, e.g. the Mariana Trench
Record
Answer
Note
Highest mountain
Mount Everest
8,849 m; Nepal–China
Deepest point
Mariana Trench (Challenger Deep)
About 11 km deep; Pacific
Longest river
Nile (Africa)
Some studies rank the Amazon longer
Most water in a river
Amazon (South America)
Largest river basin too
Largest hot desert
Sahara (Africa)
Antarctica is the largest cold desert
Largest lake
Caspian Sea (salt water)
Largest freshwater lake: Superior
Deepest lake
Baikal (Russia)
—
Largest island
Greenland
Belongs to Denmark
Largest / smallest country
Russia / Vatican City
By area
Where sources differ (the Nile against the Amazon), exams take the Nile as the longest.
QUICK CHECK
PYQ · Punjab Excise Inspector 2018 — The two smallest continents of the world are:
Tap an option to answer
Answer: C — Australia and Europe
Australia is the smallest and Europe the second smallest. Antarctica is fifth in size. The Punjab Election Kanungo 2021 paper repeated this question.
QUICK CHECK
PYQ · PPSC DDSWO 2023 — Which is the correct sequence of continents in increasing order of their population?
Tap an option to answer
Answer: A — i-North America, ii-Europe, iii-Africa, iv-Asia
Smallest to largest: North America, Europe, Africa, Asia. Option B is the same list in decreasing order — read 'increasing' carefully.
QUICK CHECK
PYQ · PSCB Manager — What is the deepest point in Earth's oceans?
Tap an option to answer
Answer: C — Mariana Trench
The Mariana Trench in the western Pacific; its Challenger Deep is about 11 km deep. It is an 'ocean deep' (PPSC AO 2022 asked that term). There is no 'Everest Trench'.
Seas, straits and canals
Rule in one line: a strait is a narrow natural sea passage between two lands; a canal is dug by people.
Tamil Nadu (left) and Sri Lanka (right) from space (NASA, 2018). The Palk Strait and Palk Bay lie to the north (top); the Gulf of Mannar lies to the south. The chain of shoals between them is Adam's Bridge (Ram Setu). Image: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC, Wikimedia Commons · Public domain
Passage
Between
Joins
Palk Strait
India – Sri Lanka
Bay of Bengal – Palk Bay
Strait of Malacca
Malaysia – Sumatra (Indonesia)
Indian Ocean – South China Sea
Strait of Hormuz
Iran – Oman
Persian Gulf – Gulf of Oman
Strait of Gibraltar
Spain – Morocco
Atlantic – Mediterranean
Bering Strait
Russia – Alaska (USA)
Pacific – Arctic
Bosporus
Europe – Asia, in Turkey
Black Sea – Sea of Marmara
Suez Canal (1869)
Egypt
Mediterranean – Red Sea
Panama Canal (1914)
Panama
Atlantic – Pacific
Straits and canals that are asked most. The Gulf of Mannar also separates India from Sri Lanka.
More places asked onceTap to open
The Caspian Sea is bordered by Kazakhstan, Russia, Azerbaijan, Iran and Turkmenistan. It is the world's largest lake.
Sumatra is Indonesia's westernmost large island; Java, Bali and Lombok lie further east.
Japan's four main islands, north to south: Hokkaido, Honshu, Shikoku, Kyushu.
China has island disputes with the Philippines and Vietnam in the South China Sea. The uninhabited Senkaku (Diaoyu) islands in the East China Sea are disputed by China and Japan.
An archipelago is a group of islands. The British Isles (Great Britain, Ireland and many small islands) form one; Sri Lanka, Madagascar and Tasmania are single large islands.
Cities on rivers: Niger – Niamey, Danube – Budapest (also Vienna and Belgrade), Congo – Kinshasa. Recife in Brazil is on the Atlantic coast, so Amazon - Recife is a wrong pair; Manaus lies on the Amazon.
Largest freshwater lakes by volume of water: Baikal – Tanganyika – Superior – Malawi. By surface area, Superior is the largest freshwater lake.
Angkor Wat, the largest religious monument in the world, is in Cambodia. The burning Darvaza gas crater ('Gateway to Hell') is in Turkmenistan.
Cuba is called the 'sugar bowl of the world'.
QUICK CHECK
PYQ · PSCB Senior Manager 2021 — Which Strait separates India from Sri Lanka?
Tap an option to answer
Answer: B — Palk Strait
The Palk Strait, between Tamil Nadu and northern Sri Lanka. SI 2023 asked the Gulf of Mannar twice; that answer is also Sri Lanka. Bali and Wetar straits are in Indonesia.
QUICK CHECK
PYQ · PSSSB Senior Assistant 2024 — It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the southwest, Iran to the south, and Turkmenistan to the southeast. Which sea is being referred to?
Tap an option to answer
Answer: A — Caspian Sea
The Caspian Sea is land-locked by exactly these five countries. The Aegean lies between Greece and Turkey.
The atmosphere, winds and ocean currents
Rule in one line: weather happens in the lowest layer; winds and currents carry heat from the tropics towards the poles.
Layer (lowest first)
Height
Remember
Troposphere
About 13 km on average
All weather; almost all water vapour and dust
Stratosphere
Up to about 50 km
Ozone layer; calm air, good for jet aircraft
Mesosphere
Up to about 80 km
Meteors burn up here
Thermosphere
About 80–400 km
Ionosphere reflects radio waves; heat rises with height
Exosphere
Above that
Very thin air fading into space
Heights from NCERT class 7. The air is about 78% nitrogen and 21% oxygen.
REMEMBER
Upwards: Tall Strong Men Take Exercise — Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere.
Local wind
Hot or cold
Where
Sirocco
Hot, dry, dusty
From the Sahara across the Mediterranean to Italy
Loo
Hot, dry
North Indian plains in May–June
Harmattan
Dry, dusty
West Africa; called 'the doctor'
Chinook / Foehn
Warm, dry
Rockies / Alps; melts snow
Mistral, Bora, Tramontana
Cold
France, the Adriatic coast, Spain–Italy
Planetary winds: trade winds blow towards the Equator, westerlies in the middle latitudes, polar easterlies near the poles.
OCEAN CURRENTS
Warm currents
Cold currents
Flow
From the Equator towards the poles
From the poles towards the Equator
Atlantic
Gulf Stream
Labrador, Canary, Benguela
Pacific
Kuroshio (Japan)
Humboldt (Peru), California
Where warm and cold currents meet — as near Newfoundland — there is thick fog and some of the world's richest fishing grounds.
QUICK CHECK
PYQ · PPSC OHE 2016 — Arrange the layers of the atmosphere in order of increasing altitude
Tap an option to answer
Answer: A — Troposphere, stratosphere, mesosphere, thermosphere
From the ground up: troposphere, stratosphere, mesosphere, thermosphere (then exosphere).
QUICK CHECK
PYQ · PPSC DDSWO 2026 — Which one of the following winds is characterized as hot, dry dusty wind that originates in Saharan desert?
Tap an option to answer
Answer: B — Sirocco
Sirocco blows from the Sahara towards southern Europe. Mistral, Tramontana and Bora are cold winds.
Inside the Earth: plates, earthquakes and volcanoes
Rule in one line: the crust is broken into moving plates; most quakes and volcanoes happen where plates meet.
1
Crust
Thin outer shell: thicker under continents, thinner under oceans.
2
Mantle
Thick hot rock layer; slowly flowing in its upper part.
3
Core
Mostly iron and nickel; outer core liquid, inner core solid.
The three layers of the Earth, outside in.
THREE KINDS OF PLATE BOUNDARY
Plates move apart
Plates collide
Plates slide past
Name
Divergent
Convergent
Transform
What forms
Mid-ocean ridge
Trench, volcanoes or fold mountains
Faults, earthquakes
Example
Mid-Atlantic Ridge
Mariana Trench; Himalaya
San Andreas Fault
At a convergent boundary the heavier oceanic plate sinks under the other into the mantle. This is subduction.The Pacific Ring of Fire. Plates sink here into the mantle, making deep trenches (blue) and chains of volcanoes. The white dot marks the Challenger Deep in the Mariana Trench. Image: Gringer, Wikimedia Commons · Public domain
KEY TERM
Focus and epicentre
An earthquake starts at the focus (hypocentre), deep inside the Earth. The point on the surface just above the focus is the epicentre; shaking is usually strongest there. A seismograph records the waves, and the Richter scale gives the size (magnitude).
Focus, deep inside→Waves travel out→Epicentre, just above
QUICK CHECK
PYQ · Punjab Police SI 2021 — The process by which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries is called:
Tap an option to answer
Answer: C — Subduction
Subduction: the dense oceanic plate dives beneath the other plate and melts back into the mantle, forming a trench.
QUICK CHECK
PYQ · PPSC SEVE 2016 — Epicentre of an earthquake is a point associated with the:
Tap an option to answer
Answer: C — point on the earth's surface just above seismic focus
The epicentre is on the surface directly above the focus. Option B describes the focus itself.
Countries: languages, currencies and people
Rule in one line: for neighbours, learn the language and the currency together.
Country
Currency
Official language
Bangladesh
Taka
Bangla (Bengali)
Sri Lanka
Sri Lankan rupee
Sinhala and Tamil
China
Renminbi (yuan)
Mandarin Chinese
Nepal
Nepalese rupee
Nepali
Bhutan
Ngultrum
Dzongkha
Pakistan
Pakistani rupee
Urdu (and English)
Myanmar
Kyat
Burmese
Maldives
Rufiyaa
Dhivehi
Wrong options you will meet: the ringgit is Malaysia's, the dirham the UAE's, the dinar belongs to Kuwait, Iraq and others.
CHINA IN TWO LINES
The Han people make up about 91–92% of China's population. Mandarin (Putonghua) is the official language; Wu, Hakka and Foochow are regional Chinese languages, not the official one.
QUICK CHECK
PYQ · Punjab Police Constable 2021 — Which of the following countries has the most Sikh population?
Tap an option to answer
Answer: A — Canada
Canada, by a wide margin among these four. Malaysia has a smaller but old Sikh community.
Traps and practice
Last revision — where the options try to fool you.
COMMON TRAPS
IST is +5:30; +5:45 is Nepal's time.
Meridians come closer towards the poles; parallels stay the same distance apart.
Smallest continents: Australia, then Europe — not Antarctica.
Epicentre is on the surface; the focus is inside the Earth.
Sirocco is hot (Sahara); Mistral and Bora are cold.
Palk Strait and Gulf of Mannar both separate India from Sri Lanka.
'Increasing order' means smallest first — check before you tick.
CHECK YOURSELF
It is 12 noon at Greenwich. What is the time at a place on 90°E?
Show answer
90 × 4 = 360 minutes = 6 hours. The place is east, so it is ahead: 12 noon + 6 hours = 6 pm.
FLASHCARDS
World geography flashcards
Time for 1° of longitude
4 minutes
India's standard meridian
82°30'E, near Mirzapur
180° longitude
International Date Line
Shortest route on the globe
Great circle
Deepest point in the oceans
Mariana Trench
World's largest lake
Caspian Sea
Layer with the ozone
Stratosphere
Hot dusty wind from the Sahara
Sirocco
Oceanic plate sinking into the mantle
Subduction
Currency of Bangladesh
Taka
QUICK BYTES
Rotation 24 h, west to east; revolution 365¼ days; axis tilt 23½°
21 June and 22 December solstices; 21 March and 23 September equinoxes
Subduction at convergent boundaries; epicentre above the focus
❧
Frequently Asked Questions
Why do we have seasons?
Because the Earth's axis is tilted while it goes round the Sun. Each half of the Earth leans towards the Sun for part of the year and gets more direct sunlight. The change in distance from the Sun is too small to matter.
How far ahead of GMT is Indian Standard Time?
5 hours 30 minutes. IST is the time of 82°30'E, and each degree of longitude equals 4 minutes.
What is the International Date Line?
An imaginary line roughly along the 180° meridian, opposite the Prime Meridian. The date changes by one day when you cross it.
How many longitudes are there on the globe?
360 degrees of longitude — 180 east and 180 west of the Prime Meridian at Greenwich. Places on the same longitude have the same time and date.
Which are the largest and smallest continents?
Asia is the largest in both area and population. Australia is the smallest, and Europe is the second smallest.
Which is the longest river in the world, the Nile or the Amazon?
Most textbooks and exams give the Nile. Some studies measure the Amazon as slightly longer. The Amazon certainly carries the most water.
Which strait separates India from Sri Lanka?
The Palk Strait. To its south lies the Gulf of Mannar, which also separates the two countries.
What are the layers of the atmosphere?
From the ground up: troposphere (weather), stratosphere (ozone, jet aircraft), mesosphere (meteors burn), thermosphere (ionosphere) and exosphere.
What is the difference between the focus and the epicentre of an earthquake?
The focus is where the quake starts, deep inside the Earth. The epicentre is the point on the surface directly above it.
What is the currency of Bangladesh and the official language of Sri Lanka?
Bangladesh uses the taka. Sri Lanka's official languages are Sinhala and Tamil.
