- A globe is a true model of the Earth.
Globe: A globe is a model of the Earth that shows the Earth’s shape, lands, oceans distances and directions as they relate t one another truly.
- The globes are of varying sizes and types.
- Globe can be rotated in the same way as a top spin or potter’s wheel is rotated.
- Axis: The imaginary line passing through the centre of the Earth and joining the two points.
- A needle is fixed through the globe in a titled manner, which is called its axis.
Advantages of the Globe
- It shows the exact shape of the Earth
- It helps us to understand how day and night occur and seasons are caused.
- It gives the ideas of tilt of the Earth's axis.
- It shows us the exact position and areas of the continents and the oceans.
Disadvantages of the Globe
- It is difficult to carry it anywhere.
- Only a part of the Globe can be seen at a time.
- It cannot be used to study the specific part of the Earth.
- It does not show towns, cities, district, roads, railways etc.
- It is the line which passes through the centre of the Earth.
- It divides the Earth into two equal parts- The Northern Hemisphere and the Southern Hemisphere
- It is the largest Latitude at 0 degree.
- It runs from east to west.
Parallels of Latitude
- Latitude is an invisible horizontal line that runs around the Earth from East to West.
- All parallel circles begin from the Equator. equator up to the poles are called parallels of latitudes.
- The Equator represents the zero degree latitude.
- Run in east-west direction.
- Measures distance north or south from the Equator.
- Are parallel to one another and never meet each other.
- Meet the Prime Meridian at right angles.
- Get shorter as they move towards the poles.
Fig: Different Zones on the Earth
Fig: Temperature of different zones on Earth
Table : Features of the Different Zones:
- Longitude is the invisible vertical line that runs around the Earth from North to South. The Prime Meridian is where its coordinates are 0°.
- Cities with a longitude of 0° include Greenwich and Cambridge (UK), Lleida (Spain) and Le Havre (France).
- Longitude divides the globe into the Eastern and Western Hemispheres along the Prime Meridian.
- The Prime Meridian originated in Greenwich, London which is why the longitude of 0° is set there. It runs through the UK, France, Africa and several seas.
- New York has a longitude coordinate of 74°W (West) and Cairo has a longitude coordinate of 31°E (East).
Fig: Time Equals Longitude
Longitude and Time
- Since the earth makes one complete revolution of 360° in one day or 24 hours, it passes through 15° in one hour or 1° in 4 minutes.
- The earth rotates from west to east, so every 15° we go eastwards, local time is advanced by 1 hour. Conversely, if we go westwards, local time is retarded by 1 hour.
- We may thus conclude that places east of Greenwich see the sun earlier and gain time, whereas places west of Greenwich see the sun later and lose time.
- If we know G.M.T., to find local time, we merely have to add or subtract the difference in the number of hours from the given longitude.
- When the prime meridian of Greenwich has the sun at the highest point in the sky, all the places along this meridian will have mid-day or noon.
The time zone are defined by dividing the 360º of the earthly sphere into the 24 hours of the day. As a result, each time zone corresponds to 15º of the Earth's circumference and is the equivalent of 1 hour.
Why do we have Standard Time?
(i) The local time of places which are on different meridians are bound to differ.
(ii) For example: In India there will be a difference of about 1 hour and 45 minutes in the local times of Dwarka in Gujarat and Dibrugarh in Assam.
(iii) In India, the longitude of is treated as the standard meridian. The local time at this meridian is taken as the standard time for the whole country. It is called Indian Standard Time.
Fig: Time Zones of India
Fig: Longitude extremes of India
Fig: Division of Earth on Basis of Latitude and Longitude