Geography Skills: Latitude and Longitude

Grid Lines Latitude and Longitude is a complicated form of a very simple concept - grid lines that divide a map into smaller square sections. Most students have used gridlines for years, with games like Battleship.

Grid Lines There are two main types of gridlines commonly used in maps: Letter-Number ex. A2 Number-Number (which can be divided into two) Four-figure ex. 0225 Six-figure ex. 023257

Letter – Number Grids Here you can see a very simple letter-number grid. What is located at: C2? B5? D2? Where is the: Red oval? Green triangle? Purple square?

Number-Number Grids Number-Number Grids are a little harder to work with, but allow for the possibility of more detail. Four-figure and Six-figure are the most common grid types.

Four-figure Grid Refences The Numbers crawling along the bottom are the Eastings. Read them first. The numbers climbing up the side are the Northings. Read them second. Remember: Babies crawl before they climb!

Six-figure Grid References Four-figure Grid References lack detail. Divide the spaces into ten equal parts to enable the use of six-figure grid references, which are more accurate.

Six-figure Grid References

The Earth Grid The earth is divided up with imaginary lines that help us measure distances. These lines are known as lines of latitude and lines of longitude.

1. Parallels of Latitude Lines of latitude run around the globe. They are parallel to each other. The longest latitude line is the Equator (0°). Lines get shorter and shorter as they get closer to the poles.

Lines of Latitude The Earth is divided into 181 parallel lines from the North Pole to the South Pole. There are 90 lines north of the Equator and 90 south of the Equator.

Lines of Latitude Major Lines of Latitude

Lines of Latitude There are 7 major lines of Latitude (as shown in Figure A).

a) The Equator: 0° The imaginary line of latitude that runs around the middle of the earth is known as the Equator. 0° latitude is called the Equator because it divides the earth into two equal halves: the Northern and Southern Hemispheres.

b) The Poles: 90°N and 90°S The 90th parallels are called the North Pole (90°N) and South Pole (90°S). They mark the earth’s axis (the line around which the earth rotates)

c) The Tropics: 23.5°N and 23.5°S Tropic of Cancer 23.5°N Tropic of Capricorn 23.5°S These imaginary lines mark the area of the earth that can have the sun directly overhead. Between these lines is the hottest part of the world (the tropics).

d) The Circles: 66.5°N and 66.5°S The Arctic Circle 66.5°N The Antarctic Circle 66.5°S These imaginary lines mark the zones of twenty-four hour darkness or light.

d) The Circles: 66.5°N and 66.5°S In winter, the areas between these lines and the corresponding pole will be dark for several months. In summer, these areas will experience twenty-four hour daylight for several months.

2. Meridians of Longitude On the globe there are imaginary lines that run from the North Pole to the South Pole. These lines are called meridians or longitude lines.

Lines of Longitude Another way to see lines of longitude (showing their degrees as the 360° of a circle):

Lines of Longitude There are 360 meridians. Meridians are numbered from the 0° going East to 180° and going West to 180°. These numbers represent the distance from the Prime Meridian.

Meridians of Longitude Figure B shows the two most important meridians and how meridians are drawn on a map with a view from above the North Pole.

Prime Meridian The most important line of longitude is the Prime Meridian (0⁰). This line runs through Greenwich, England (so it is also called the Greenwich Meridian). All other lines are measured either East or West of this line.

Different Prime Meridians Washington, D.C. (77° 3' 2.3” W Rio de Janeiro (43° 10' 19” W)[2] Madrid (3° 41' 16.58” W) Paris (2° 20' 14.025” E) Rome (12° 27' 08.4” E) Alexandria (29° 53' E) Saint Petersburg (30° 19' 42.09” E) Jerusalem (35° 13' 47.1” E) Ujjain (75° 47' E) Kyoto (135° 74' E) Mecca (39° 49′ 34″ E)

International Date Line Directly across from the Prime Meridian is the International Date Line, which approximately follows the 180° Meridian. This line moves a little bit in order to go around land masses and islands.

International Date Line At this line, the date changes one entire day. For instance, if it is Monday in China, it is Sunday in Canada. If it is Tuesday in Tonga, it is Monday in Samoa at exactly the same time!

Reading Coordinates (Latitude and Longitude) The longitude and latitude of a place are called its coordinates. Longitude and latitude are first measured in degrees. Each degree can then be divided into sixty parts called minutes for more accuracy. Likewise, each minute can be divided into sixty parts called seconds in order to be very accurate.

Reading Coordinates (Latitude and Longitude) Degrees are usually shown with a °. Minutes are usually shown with a ´. Seconds are shown with a ˝. Sometimes, the symbols for degree, minute, and second are not actually given. Seconds are very accurate and would be used to show detail. Empire State Building, New York, NY LATITUDE LONGITUDE 40° 44′ 54″ N 73° 59′ 08″ W

Reading Coordinates (Latitude and Longitude) Empire State Building, New York, NY LATITUDE LONGITUDE 40° 44′ 54″ N 73° 59′ 08″ W For example, New York could be shown with degrees and minutes. Seconds would be used to show the location of places in New York, such as the Empire State Building.

Rounding-Off Coordinates In an atlas, the coordinates are usually given with both degrees and minutes. Often the minutes are not actually needed and actually make it harder to find a location on a map. In these situations, it is important to know how to round off.

Rounding Off – Think of Half

Rounding-Off Coordinates When thinking of rounding off, it is important to remember that there are 60 minutes in one degree. So, half of that is 30 minutes. Anything below 30 minutes will round down. Anything 30 minutes or higher will round up. 30 minutes or higher? ROUND UP 29 minutes or lower? ROUND DOWN

Rounding-Off Coordinates Example 1: Langley is located at 49° 06′ N 122° 40′ W   If we need to round off, we need to remember that there are sixty minutes in each degree. If we wrote these coordinates as a mixed fraction it would look like this: Langley is located at 49° 06 60 ′ N 122° 40 60 ′ W In this example 49° 06 60 ′ N would round down to 49° N, since 06 60 ′ is less than 30 60 ′. However, 122° 40 60 ′ W would round up to 123° W, since 40 60 ′ is more than 30 60 .

Exercise Round off the following sets of coordinates. 1. 14°32′ N 22°28′ W 2. 80°50′ S 30°15′ E 3. 25°30′ N 29°30′ E 4. 89°50′ N 179°05′ W

Exercise Round off the following sets of coordinates. 1. 14°32′ N 22°28′ W 2. 80°50′ S 30°15′ E   3. 25°30′ N 29°30′ E 4. 89°50′ N 179°05′ W

Latitude & Longitude: Basic Skills There are two basic skills you need to master in order to use latitude and longitude: Find a place when you are given the coordinates. Find the coordinates when you are given the name of a place.

Part 1: Find a place when you are given the coordinates. Step 1 Round off to the nearest degree if necessary. Step 2 Find the nearest major latitude & longitude lines (usually every 10°). Step 3 Find the intersection of those lines. Step 4 Move from that intersection to where you estimate the coordinates are.

Part 1: Find a place when you are given the coordinates. Q. 4°N 8°E 7°S 32°E 14°35’N 28°28’E 8°42’S 3°13’E 27°46’N 36°20’E O. M. N. P.

Part 2: Find the coordinates when you are given the name of a place. Step 1 Find the location on the map. Step 2 Move from that location to the nearest intersection of major lines (usually every 10°). Step 3 Find out the coordinates of that major intersection Step 4 Estimate the coordinates to the nearest degree. Step 5 Estimate the minutes, if necessary. Step 6 Check your answers in the gazetteer if it is available.

Part 2: Find the coordinates when you are given the name of a place.

Part 2: Find the coordinates when you are given the name of a place.

Time Zones The earth is divided into 25 different time zones.

Time Zones They are separated by one hour intervals.

Time Zones There is a new time zone roughly every 15 degrees of longitude.

Time Zones The zones are measured in hours behind or ahead of Greenwich Mean Time (GMT), which is the time at the Prime Meridian Line.

Time Zones Governments can change their country’s time zone. So for convenience the whole country can be on the same time.