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Unit 21: Finding the location and time of our destinations (A)What are latitudes and longitudes ? Latitudes and longitudes Are north-south and east-west imaginary lines drawn on the earth’s surface Are similar to grid lines Are measured in degrees (1 degree = 60 minutes; 1 minute = 60 seconds) Show the absolute location of a place on the earth Next
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Unit 21: Finding the location and time of our destinations Latitudes For examples: The latitude of Hong Kong is 22 N and Sydney is 33 S. Are numbered in degrees from 0 to 90 The equator is latitude 0 - the longest latitude which divides the earth into Northern Hemisphere and Southern Hemisphere. A place north of the equator is marked a number of degree north; whereas a place south of the equator is marked a number of degree south. The North Pole and South Pole are 90°N and 90°S. Are imaginary lines running parallel from west to east around the earth Next
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Unit 21: Finding the location and time of our destinations Longitudes Are imaginary lines running from north to south which join the two poles Are also called meridians The meridian passing through Greenwich near London is the Prime Meridian. For examples: Hong Kong is 114 E and New York is 76 W. All longitudes to the Greenwich meridian’s east are marked east; whereas those to the Greenwich meridian’s west are marked west 180 E and 180 W are in fact the same line, so it is just called 180 . Next
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Unit 21: Finding the location and time of our destinations (B)How do we find the latitude and longitude of a place from an atlas ? Suppose we want to find the location of Guangzhou in an atlas: We should look for the place in the index We may have the following information: Guangzhou23 5N113 10E 28 LatitudeLongitudePage The last number is the page on which you can find a map showing Guangzhou. When you turn to page 28 in the atlas, you can find the location of Guangzhou. Next
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Unit 21: Finding the location and time of our destinations (C)How do we find the local time and standard time of our destinations ? Using longitudes to work out the time of different parts of the world There are 360 of longitude The earth rotates on its axis from west to east. It takes 24 hours to complete one rotation. This means the earth takes 4 minutes to rotate by 1 of longitude and one hour to rotate by 15 . We can use longitudes to work out the time of different places. Hong Kong is on 114 E. If our time is 8 a.m., then the place on 129 E should be one hour ahead of us, i.e. 9a.m. whereas the place on 99 E should be one hour behind us, i.e. 7 a.m. Next
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Unit 21: Finding the location and time of our destinations Local time Is worked out based on the longitude of the place For every 1 of longitude east of Hong Kong, the local time will be 4 minutes ahead of our local time Likewise, for every 1 of longitude west of Hong Kong, the local time will be 4 minutes behind our local time Next
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Unit 21: Finding the location and time of our destinations Standard time If every place sticks to its local time, it will be very confusing. In order to solve this problem, the earth is divided into 24 time zones. Each time zone covers 15 degrees of longitudes. There is a difference of one hour between one time zone and the next. All the places within the same time zone have the same standard time. Next Big countries like China cannot give one single time because they extend a large number of longitudes.
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Unit 21: Finding the location and time of our destinations Examples: Hong Kong lies in the Standard Time Zone of 120°E; whereas London lies in that of 0°. Therefore, the Standard Time of Hong Kong is 8 hours ahead of London. Next
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Unit 21: Finding the location and time of our destinations Terms to learn: Latitude - an imaginary line running across the world from west to east Longitude/meridian - an imaginary line running from north to south joining the two poles The Prime meridian - the 0° longitude passing through Greenwich near London. It is also called the Greenwich meridian. End
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Unit 21: Finding the location and time of our destinations Latitudes Back
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Unit 21: Finding the location and time of our destinations Longitudes Back
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Unit 21: Finding the location and time of our destinations Standard time Back
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