Spheres of the earth and landforms
From space the earth looks like a blue ball with white clouds, brown land and green patches. These show the four layers of the earth that help life: land, water, air and the living world.
The earth has the lithosphere (शिलावरण, land), hydrosphere (जलावरण, water), atmosphere (वातावरण, air) and biosphere (जीवावरण, living world).
Rule 1: The four spheres — The four spheres are connected: a river (water) flows on land, birds (living) fly in the air, and rain (water) falls from the sky.
In the figure : In the figure the earth has four connected spheres.
- Easy : Easy: Land belongs to the lithosphere.
- Medium : Medium: Air belongs to the atmosphere.
- Exam-type : Exam: A fish lives in the hydrosphere and is part of the biosphere.
Rule 2: Land and continents — About one-third of the earth's surface is land. The land is divided into seven continents; Asia is the largest and Australia the smallest. Plains, hills, mountains and plateaus are landforms (भूरूपे).
In the figure : In the figure one third of the earth is land and two thirds is water.
- Easy : Easy: There are seven continents.
- Medium : Medium: If the earth is cut into 12 equal parts, 4 are land.
- Exam-type : Exam: Asia is the largest and Australia the smallest continent.
Four spheres: litho, hydro, atmo, bio. One-third land, seven continents.
Saying land covers most of the earth. Two-thirds is water.
Memory clue: "शिला = दगड, जल = पाणी, वात = हवा, जीव = प्राणी".
Spot the difference
| Sphere | Meaning |
|---|---|
| Lithosphere | Land |
| Hydrosphere | Water |
| Atmosphere | Air |
| Biosphere | Living world |
Practice questions
- 1Name the four spheres of the earth.
- 2Which sphere is the land?
- 3What fraction of the earth is land?
- 4How many continents are there?
- 5Which is the largest continent?
- 6Name two landforms.
- 7Of a map divided into 9 equal parts for the earth, how many show water?
- 8A bird drinks river water on a hill. Which spheres are linked?
Show answers (try them yourself first)
- 1Lithosphere, hydrosphere, atmosphere and biosphere.
- 2Lithosphere.
- 3One-third.
- 4Seven.
- 5Asia.
- 6Plains and mountains.
- 7Two-thirds of 9 = 6.
- 8Biosphere, hydrosphere and lithosphere.
The hydrosphere
The sea water at a beach tastes salty, but the water from a tap tastes sweet. Most of the earth's water is the salty kind.
The hydrosphere is all the water of the earth. About two-thirds of the surface is water.
Rule 1: Salty and fresh water — Ocean water is salty, and there are five oceans. Rills, brooks, streams and rivers carry fresh water. A tributary (उपनदी) is a smaller river that joins a bigger river. Lakes, glaciers (हिमनद्या), icebergs (हिमनग) and groundwater (भूजल, water from wells) are other water bodies.
In the figure : In the figure ocean water is salty; rivers, glaciers and groundwater hold fresh water.
- Easy : Easy: Ocean water is salty.
- Medium : Medium: A tributary joins a bigger river.
- Exam-type : Exam: Well water is groundwater.
Rule 2: Counting water — There are five oceans. If two-thirds of the earth is water, then in 9 parts of the earth 6 parts are water and 3 are land. We can drink only fresh water, so we must save it.
- Easy : Easy: 6 of 9 parts are water.
- Medium : Medium: Salty ocean water cannot be drunk directly.
- Exam-type : Exam: Save fresh water because it is limited.
Two-thirds water; five oceans salty; rivers, glaciers, groundwater fresh.
Thinking glaciers hold salty water. They hold fresh water.
Memory clue: "समुद्र = खारट, नदी = गोड".
Spot the difference
| Water body | Type of water |
|---|---|
| Ocean | Salty |
| River, stream | Fresh |
| Glacier, iceberg | Fresh (frozen) |
| Well | Groundwater |
Practice questions
- 1What fraction of the earth is water?
- 2How many oceans are there?
- 3Is ocean water fresh or salty?
- 4What is a tributary?
- 5Name two kinds of fresh water bodies.
- 6What is groundwater?
- 7How many of 12 equal parts of the earth are water?
- 8Why should we save fresh water?
Show answers (try them yourself first)
- 1Two-thirds.
- 2Five.
- 3Salty.
- 4A smaller river that joins a bigger river.
- 5Rivers and lakes (also glaciers, groundwater).
- 6Water under the ground that we get from wells.
- 78.
- 8It is a small part of all water, and we need it to drink and grow food.
The atmosphere
When you climb a high mountain, breathing becomes harder because the air gets thinner. This shows the air around the earth has layers.
The atmosphere (वातावरण) is the layer of air around the earth. It has layers, such as the troposphere (तपांबर) and the stratosphere (स्थितांबर).
Rule 1: What air has and its layers — Air contains nitrogen (about 78 of every 100 parts), oxygen (about 21), water vapour and carbon dioxide. The layers are the troposphere (up to about 13 km, where weather happens), the stratosphere (up to about 50 km, with the ozone layer), the mesosphere, the ionosphere and the exosphere.
In the figure : In the figure the weather happens in the troposphere, and the ozone layer in the stratosphere protects us from harmful rays.
- Easy : Easy: Clouds and rain are in the troposphere.
- Medium : Medium: The troposphere reaches about 13 km.
- Exam-type : Exam: The stratosphere reaches about 50 km, so it extends 50 − 13 = 37 km above the troposphere.
Rule 2: Ozone layer — The ozone layer (ओझोन थर), in the stratosphere, absorbs harmful ultraviolet rays of the sun. Without it, the rays would harm plants, animals and people.
- Easy : Easy: Ozone protects us.
- Medium : Medium: Ozone is in the stratosphere.
- Exam-type : Exam: It absorbs harmful ultraviolet rays.
Weather: troposphere. Ozone: stratosphere. Air: nitrogen, oxygen, vapour, carbon dioxide.
Saying air is only oxygen. Most of it is nitrogen.
Memory clue: "तप = हवामान, स्थित = ओझोन".
Spot the difference
| Layer | Height and role |
|---|---|
| Troposphere | To about 13 km; weather |
| Stratosphere | To about 50 km; ozone layer |
Practice questions
- 1What is the atmosphere?
- 2Name two gases in air.
- 3Which layer has the weather?
- 4Where is the ozone layer?
- 5What does the ozone layer do?
- 6How high does the troposphere go?
- 7A plane flies at 10 km. Which layer is it in?
- 8Of every 100 parts of air about 78 are nitrogen and 21 oxygen. How many parts are other gases?
Show answers (try them yourself first)
- 1The layer of air around the earth.
- 2Nitrogen and oxygen.
- 3Troposphere.
- 4In the stratosphere.
- 5It absorbs harmful ultraviolet rays.
- 6About 13 km.
- 7The troposphere (below 13 km).
- 8100 − 78 − 21 = 1 part.
The water cycle
Wet clothes dry on a clothesline in the sun. The water goes into the air as invisible vapour, rises, makes clouds and comes back as rain.
The water cycle (जलचक्र) has three main steps: evaporation (बाष्पीभवन), condensation (संघनन) and rainfall (पर्जन्य).
Rule 1: Steps of the water cycle — The heat of the sun turns water into vapour (evaporation). The vapour rises, cools and turns into clouds of tiny droplets (condensation). Droplets join and fall as rain (rainfall). The water flows back to the sea, and the cycle goes on.
In the figure : In the figure the water cycle never stops: evaporation, condensation, rainfall, and back to the sea.
The water cycle
In the app you can move this figure with your finger.
Open in the app- Easy : Easy: Sun heat causes evaporation.
- Medium : Medium: Clouds are tiny droplets, formed by condensation.
- Exam-type : Exam: The cycle goes on because water keeps returning to the sea.
Evaporation → condensation → rainfall → sea.
Mixing up evaporation and condensation. Evaporation goes up; condensation makes clouds.
Memory clue: "वर जाते बाष्प, ढग बनते संघनन, खाली येतो पर्जन्य".
Spot the difference
| Step | What happens |
|---|---|
| Evaporation | Water becomes vapour by heat |
| Condensation | Vapour becomes droplets and clouds |
| Rainfall | Droplets fall as rain |
Practice questions
- 1Name the three steps of the water cycle.
- 2What causes evaporation?
- 3What are clouds made of?
- 4What is condensation?
- 5Where does rainwater finally go?
- 6Why does wet cloth dry in the sun?
- 7Why does the water cycle never stop?
- 8A glass of cold water has drops outside on a warm day. Which step is this?
Show answers (try them yourself first)
- 1Evaporation, condensation and rainfall.
- 2The heat of the sun.
- 3Tiny droplets of water.
- 4Vapour cooling into tiny droplets.
- 5Back to the sea.
- 6Heat evaporates the water.
- 7The sun keeps heating, and water keeps returning to the sea.
- 8Condensation of vapour from the air.
The biosphere
A polar bear lives in snow, a zebra on grassland and a kangaroo in Australia. Each animal lives where its needs are met. All of them together with plants form the living world.
The biosphere (जीवावरण) is all the living things on land, in water and in air, with the parts of the earth they occupy.
Rule 1: Living things in each region — Each region has its own plants and animals, for example the polar bear, the zebra and the kangaroo. All living things depend on one another and on air, water and soil.
In the figure : In the figure each region has its own plants and animals, and they depend on one another.
- Easy : Easy: A polar bear lives in the cold.
- Medium : Medium: A zebra lives on grassland.
- Exam-type : Exam: Plants and animals depend on one another.
Rule 2: All spheres together — The biosphere needs the other three spheres: land to stand and grow on, water to drink, and air to breathe. If one sphere is polluted, the living world suffers.
- Easy : Easy: Living things need air.
- Medium : Medium: Dirty water harms living things.
- Exam-type : Exam: A healthy biosphere needs clean land, water and air.
Biosphere = all living things and the places they live in.
Thinking animals can live anywhere. Each lives where its needs are met.
Memory clue: "जीवावरण = सजीवांचे घर".
Spot the difference
| Animal | Region |
|---|---|
| Polar bear | Cold polar region |
| Zebra | Grassland |
| Kangaroo | Australia |
Practice questions
- 1What is the biosphere?
- 2Name an animal of the polar region.
- 3Where does a kangaroo live?
- 4Which animal lives on grassland?
- 5What do living things need from the other spheres?
- 6Why do living things depend on one another?
- 7What happens to the biosphere if the air is polluted?
- 8Why can a polar bear not live in a desert?
Show answers (try them yourself first)
- 1All living things and the places they occupy.
- 2Polar bear.
- 3In Australia.
- 4Zebra.
- 5Land, water and air.
- 6They give each other food, shelter and oxygen.
- 7Living things fall sick or die.
- 8It is made for cold snowy places and would suffer from heat and lack of its food.
Quick revision
- Four spheres: litho, hydro, atmo, bio.
- 1/3 land, 2/3 water; troposphere has weather; ozone is in the stratosphere.
- Water cycle: evaporation, condensation, rainfall.