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Understanding Earth's Grid System: Latitude, Longitude, and Time Zones Explained

Explore Earth's grid system, including latitudes, longitudes, time zones, and the International Date Line, to locate places and understand global climate zones and time differences.

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Navya Rai Ch 2 – Locating Places through Grid System Class 6 SS Geo
▣ On the Earth’s surface, we use some fixed points and imaginary lines as references to help us find various places. ▣ Earth rotates on its own axis. ▣ The endpoints of the axis of the Earth are called poles. ▣ The northern end of this axis is called the North Pole. ▣ The opposite end is called the South Pole
▣ The globe is used as a true representation of the Earth because it is modelled after the shape of the Earth. The first globe was made by Martin Behaim in 1492
▣ The Earth’s surface is vast. To find places imaginary lines called latitudes and longitudes are drawn on a globe.
▣ The imaginary horizontal lines drawn on Earth from east to west are the lines of latitude. All these lines run parallel to each other. And so they are called parallels of latitude. They are of different length.
▣ There are four important parallels of latitude: i
Temperature decreases from the equator towards the poles. So the latitudinal zones are the actual heat zones of the earth, namely tropical/torrid, temperate and polar/frigid zones. Tropical/Torrid zone: Hottest zone of earth. Temperate zone: Moderate, Sun never shines vertically here. Frigid/Polar zone : Coldest zones of earth.
▣ Different places on the Earth receive different amount of sunlight. ▣ The Sun’s rays are concentrated in the areas near the Equator.
▣ Frigid zone is lies between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere.
▣ The Temperate Zone is located between the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere. ▣ And the Tropic of Capricorn and the Antarctic circle in Southern Hemisphere. ‘Temperate’ means ‘moderate’. These area experiences mild and moderate climate.
▣ The regions lying between the Tropic of Cancer and the Tropic of Capricorn get the midday Sun overhead at least once in a year. This region known as Torrid Zone or Tropical Zone.
▣ Longitude is the measurement east or west of the prime meridian. ▣ Longitude is measured by imaginary lines that run around the Earth vertically (up and down) and meet at the North and South Poles. These lines are known as meridians. ▣ Each meridian measures one arcdegree of longitude. The distance around the Earth measures 360 degrees.
▣ The meridian that runs through Greenwich, England, is internationally accepted as the line of 0 degrees longitude, or the prime meridian. The antemeridian is halfway around the world, at 180 degrees. It is the basis for the International Date Line.
▣ A pattern of crossed lines formed by lines of latitudes and longitudes are called global grid.
▣ The Earth moves at a constant rate, covering 360° of arc in 24 hours. The following relationships exists between time and arc: ▣ Time Arc ▣ 24 hours 360° ▣ 1 hour 15° ▣ 4 minutes 1° ▣ The Earth rotates west to East.
▣ The Earth completes the rotation of 360 degree in one day or 24 hours. ▣ It rotates 15 degree in one hour or 1 degree in 4 minutes. ▣ The Earth rotates west to east, so for every 15 degree we go eastwards, the time is advanced by 1 hour. ▣ Thus, it can be concluded that places east of Greenwich see the Sun earlier and are ahead in time. ▣ The 24 hours period of a day divided into two time periods- 12 hours before noon (a.m) and 12 hours after noon (p.m)
● Time can be measured on the basis of the movement of the Sun, Moon, etc. ● Midday occurs at different times at different meridians. ● One rotation of earth = 24 hours = 360° of longitudes. ● So, 1 hour = 15° of longitudes ● 1° = 4 minutes ● Therefore, 12 noon at the prime meridian will be 1 p.m. at the 15°E meridian, 11 a.m. at the 15°W meridian. Time and Longitudes
▣ If we know the Greenwich Mean Time (GMT) we can find out the local time of an area by adding or subtracting the difference in time from the GMT.
▣ If each place determines its time on the basis of its meridian, there will be much difference in local time from one town to the other. ▣ In order avoid such situations and confusion standard time is followed by most countries. The countries decide their standard time based on their central meridian
▣ The Indian Government has adopted the meridian 82°1/2' E, which passes through Mirzapur, near Allahabad (formerly Prayagraj) in Uttar Pradesh, as the Indian Standard Time meridian.
▣ The International Date Line, established in 1884, passes through the mid- Pacific Ocean and roughly follows a 180 degrees longitude north-south line on the Earth. ▣ It is located halfway round the world from the prime meridian—the zero degrees longitude established in Greenwich, England, in 1852.
Locating places within the grid: • To precisely locate points on the Earth’s surface, degrees of longitude and latitude have been divided into minutes (') and seconds ("). • There are 60 minutes in each degree. Each minute is divided into 60 seconds. Seconds can be further divided into tenths, hundredths, or even thousandths.
Brainstorm Which country has no night and why? Does it happen throughout the year? Why there is 6 months day and 6 months night at some places? Does India have same time zones throughout the country? Justify.
Do you know? Majorly Norway. Also known as the Land of the Midnight Sun, Norway, for a period of 76 days never experiences sunset. That period is from May until the end of July, where there is constant sunlight. The city of Svalbard in the country experiences constant sunshine from April 10 to August 23.(Other countries like canada, ice land, alaska, Finland) The Poles experience about six months of day and six months of night because of the tilt of the Earth on its axis. Because of this tilt each Pole is tilted towards and away from the Sun for about six months each. When the North Pole is tilted towards the Sun it experiences continuous daylight for six months.
Does India have same time zones throughout the country? The Republic of India uses only one time zone (even though it spans across two-three geographical time zones) across the whole nation and all its territories, called Indian Standard Time (IST), which equates to UTC+05:30, i.e. five and a half hours ahead of Coordinated Universal Time (UTC). UTC is also known as GMT Greenwich Mean Time.