What is a map? What are its main components?
A map is a drawing or representation of an area, such as a village, town, state, country, or even the whole world. It shows places as if viewed from the top. Maps help us locate places and understand directions and geographical features.
An atlas is a book or collection of maps.
Benefits of Maps
- Maps show detailed information about places, including streets, landmarks, and natural features.
- Maps are easy to carry and store, whether on paper or in digital form.
- Maps can show specific information like climate, population, country borders, or natural resources.
- Maps use symbols and scales, making them easy to read and understand.
- Maps help us see complex information in a simple way, such as rainfall, forests, population, or election results.
Different Types of Maps
Physical Maps
Maps that show natural features of the earth such as mountains, plateaus, plains, rivers, oceans, etc. are called physical or relief maps.
Eg. World Ocean Map, Mountain Ranges Map
Political Maps
Political maps show the boundaries and divisions between countries, states, and cities. They show human-made features such as countries, states, union territories cities, towns, and villages with clearly defined borders.
Eg. India Map with States, Districts and UT
Thematic Maps
Thematic maps are designed to show a specific theme or piece of information, such as climate, population, industries, or roads, crops, rainfall, railways, disease outbreaks, etc. They help to analyse particular aspects of a region.
Components of a Map:
Distance
Distance on a map shows how far apart two places are in real life. To measure this, maps use a scale, which compares the map’s distance to the actual ground distance. The scale helps in determining the actual distance between two spots on a map.
Eg. If the scale of a map is 1 cm = 10 km, and the distance between two cities on the map is 5 cm, the actual distance between them is 5 × 10 = 50 km.
Direction
The cardinal points are the four major directions of North, South, East, and West.
There are also four intermediary routes. North-east, south-east, north-west, and south-west are the directions.
A compass is used to determine a location's direction.
Symbols
Symbols are small pictures, colors, or letters used on maps to represent real things like houses, roads, rivers, railway lines and mountains. Through symbols numerous things can be shown on a map. For example, blue shows water, brown shows mountains, yellow shows plateaus, and green shows forests and plains. Symbols make maps easy to read and understand.
Mapping the earth
Earlier times, people considered the world as a flat disc. It extends indefinitely in all the four directions.
By the time of the ancient Greeks (BC 1200-900), many people believed that the Earth was spherical.
Ancient Greek philosophers, Aristotle, argued that the Earth was a sphere based on his observations of the stars.
Ferdinand Magellan's crew started their sail from Europe and returned back to the same spot by circumnavigating the earth.
Isaac Newton first proposed that Earth was not perfectly round. Instead, he suggested it was an oblate spheroid—a sphere that is flattened at its poles and bulged in the middle.
What is a Globe? A globe is a model of the Earth that represents its actual shape more accurately than a flat map.
Mapping the Earth is difficult because our planet is not a flat surface but in the shape of an oblate spheroid. (Flattened at the poles and bulged in the middle)
When we try to show this earth's shape on flat paper, it causes changes in the size, shape, distance, and direction of countries and oceans.
In this, the actual representation of the Earth is not possible.
Thus, the globe is used for mapping the Earth because both the Earth and the globe have the same spherical shape.
How do we locate any places on a map?
To locate a map, a system of coordinates is used. This includes latitudes and longitudes. It helps in locating the location of a map.
Latitudes
The imaginary line that runs around the middle of the earth is called Equator. It divides the globe into two equal parts: Northern Hemisphere and Southern Hemisphere.
All parallel circles from the Equator up to the poles are called parallels of latitude. The largest circle is the Equator.
Latitude is measured in degrees.
The Equator is 0° (zero degrees) latitude, while the latitudes of the two poles are 90° North and 90° South respectively.
There is a relationship between latitude and climate. Near the Equator, the climate is generally hot (also called torrid).
As we move away from the Equator towards one of the two poles, the climate becomes more moderate (or temperate).
As we move closer to the North or South Pole, the climate becomes colder (or ‘frigid’).
Other four important parallels of latitude are:
Tropic of Cancer (23 1/2° N)
Tropic of Capricorn (23 1/2° S)
Arctic of Circle (66 1/2° N)
Antarctic Circle (66 1/2° S)
Longitude
The imaginary lines of half-circles running from one pole to the other are called meridians of longitude.
To measure longitudes, we need to define a reference point called the Prime Meridian.
It is also called the Greenwich Meridian because, in the year 1884, some nations decided that the meridian passing through Greenwich, an area of London in England, would become the international standard for the Prime Meridian. It is marked as 0° longitude. (It also passes through British Royal Observatory)
The Prime Meridian divides the Earth into the Western and Eastern Hemispheres.
Longitude is a measure of the distance in degrees from the Prime Meridian.
Longitudes are measured in the East and West directions. The values of longitudes are between 0° to 180°.
By measuring the longitude of a place, we can also measure the time at that place.
Latitude and longitude together are the two coordinates of a place. With the help of these co-ordinates, we can locate any place on Earth.
Important Note
What is a grid line on a globe?
To locate a place on the Earth all the lines of latitudes and longitudes together constitute a grid for the globe. They are also called grid lines.
180° W and 180° E are the same longitude on the globe. Hence, this longitude is noted as 180°, without the letter W or E.
What was India’s ancient prime meridian, and which city did it pass through?
Many centuries before the Greenwich Meridian, India had its own prime meridian called the Madhya Rekha or ‘middle line’.
It passed through Ujjayini (modern-day Ujjain), a renowned centre of astronomy. Famous astronomer Varahamihira worked there around 1,500 years ago.
Indian astronomers understood the concepts of latitude and longitude and used Ujjayini as the reference point for calculations in ancient texts.
The Earth and Time Zones:
OR
How are time zones related to the Earth’s rotation?
The Earth rotates from west to east, completing one full turn (360°) in 24 hours.
This means the Earth rotates 15° every hour (360 ÷ 24 = 15).
This means that every 15° the Earth turns, 1 hour passes.
To help measure time across the world, the Earth is divided into 24 time zones, each covering 15° of longitude. The starting point is the Prime Meridian (0° longitude) at Greenwich, London (GMT Greenwich Mean Time)
Moving east from Greenwich, we add 1 hour for every 15° of longitude:
At 15°E, it is 1 pm when it's 12 noon at Greenwich.
At 30°E, it is 2 pm, and so on.
Moving west, we subtract 1 hour for every 15° of longitude:
At 15°W, it is 11 am when it's 12 noon at Greenwich.
At 30°W, it is 10 am, and so on.
The Earth rotates from west to east.
Arunachal Pradesh lies in the easternmost part of India, while Gujarat lies in the westernmost part.
The longitudinal difference between Arunachal Pradesh and Gujarat is about 30°.
The Earth rotates 360° in 24 hours, i.e., 15° per hour.
So, for 30° difference, the time gap is 2 hours (30 ÷ 15 = 2).
This means the Sun rises about 2 hours earlier in Arunachal Pradesh than in Gujarat.
International Standard Line
International Standard Line usually means the International Date Line, an imaginary line on Earth where the date changes by one day when crossed. It is located around 180° longitude, mostly across the Pacific Ocean.
What is meant by Indian Standard Time? Why do we need a Standard Meridian in India?
From South to North. India extends between 8°4′ N and 37°6′ N latitudes.
- From West to East, India extends between 68°7′ E and 97°25′ E longitudes.
- The local time various places are different, so it is necessary to adopt the local time of some central meridian of a country as the Standard Time.
- 8212°E is treated as the Standard Meridian of India. The local time at this meridian is known as the Indian Standard Time (IST).
- India located East of Greenwich at 82° 30’E, is 5 hours and 30 minutes ahead of GMT.
- Some countries have a great longitudinal extent and so they have adopted more than one standard time.
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