Globes, Hemispheres, Latitude & Longitude: Fifth Grade Social Studies
Globes and the geographic grid system provide the foundational tools that allow cartographers and navigators to locate any point on Earth with mathematical accuracy.
The Model of Our Planet: The Globe
A globe is a three-dimensional, spherical scale model of the Earth. Because the Earth is an oblate spheroid—a sphere slightly flattened at the polar regions and bulging at the equator—a globe represents the true shapes, relative sizes, directions, and distances of continents and oceans without the distortions unavoidable on flat paper maps.
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| EARTH'S HEMISPHERIC DIVISIONS |
| |
| NORTHERN HEMISPHERE SOUTHERN HEMISPHERE |
| - North of the Equator (0°) - South of the Equator (0°) |
| - Contains North America, Europe, - Contains Australia, |
| Asia, northern South America, Antarctica, most of South |
| and two-thirds of Africa. America, one-third of Africa |
| |
| EASTERN HEMISPHERE WESTERN HEMISPHERE |
| - East of Prime Meridian (0°) - West of Prime Meridian (0°) |
| to the 180° Antimeridian. to the 180° Antimeridian. |
| - Contains Europe, Africa, Asia, - Contains North America, |
| and Australia ("Old World"). South America ("New World"). |
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The Hemispheres
The prefix "hemi-" means half, so a hemisphere is half of the terrestrial sphere. The Earth can be divided into four distinct hemispheres using two fundamental baseline boundary rings:
- The Equator divides the globe into the Northern Hemisphere and the Southern Hemisphere. When it is summer in the Northern Hemisphere, the Earth's axial tilt causes the Southern Hemisphere to experience winter.
- The Prime Meridian (0 degrees) and its opposite counterpart, the International Date Line / Antimeridian (180 degrees), divide the Earth into the Western Hemisphere and the Eastern Hemisphere. The United States lies entirely within the Northern and Western Hemispheres.
Lines of Latitude: Parallels
Lines of latitude are imaginary horizontal reference rings that wrap around the globe from east to west, measuring angular distance in degrees north or south of the Equator.
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| KEY PARALLELS OF LATITUDE |
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| Parallel Line Name | Degree Measure | Geographic Significance |
+--------------------------+-------------------+---------------------------+
| North Pole | 90° N | Northernmost point on axis|
| Arctic Circle | 66.5° N | Boundary of polar sun |
| Tropic of Cancer | 23.5° N | Northernmost overhead sun |
| Equator | 0° | Widest terrestrial girdle |
| Tropic of Capricorn | 23.5° S | Southernmost overhead sun |
| Antarctic Circle | 66.5° S | Boundary of southern polar|
| South Pole | 90° S | Southernmost point on axis|
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Characteristics of Latitude
Latitude lines are officially called parallels because they never touch or intersect one another; they remain an equal distance apart all the way from the Equator to the poles. The Equator is designated as 0 degrees latitude. Parallels increase in value as you travel north toward the North Pole at 90 degrees North, or south toward the South Pole at 90 degrees South. Each degree of latitude represents approximately 69 miles (111 kilometers) of ground distance on the Earth's surface.
Special Parallels and Tropical Zones
The Earth is tilted on its rotational axis at an angle of approximately 23.5 degrees. This tilt creates special parallels that mark climatic zones:
- The Tropics: The zone between the Tropic of Cancer (23.5 degrees North) and the Tropic of Capricorn (23.5 degrees South) receives the most direct, intense sunlight year-round and is known as the tropical zone or low latitudes.
- The Temperate Zones: Situated between 23.5 degrees and 66.5 degrees in both hemispheres, these middle latitudes experience four distinct seasons with warm summers and cold winters.
- The Polar Zones: Situated beyond 66.5 degrees North (Arctic Circle) and 66.5 degrees South (Antarctic Circle), these high latitudes experience extreme cold and periods of 24-hour darkness or continuous daylight.
Lines of Longitude: Meridians
Lines of longitude are imaginary vertical lines that run from pole to pole, measuring angular distance in degrees east or west of the Prime Meridian.
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| THE GLOBAL LATITUDE / LONGITUDE GRID |
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| North Pole (90° N) |
| | | | |
| 60° N ---------------+---+--------------- 60° N |
| | | | |
| 30° N ---------------+---+--------------- 30° N |
| | | | |
| Equator 0° ===============+===+=============== Equator 0° |
| | | | |
| 30° S ---------------+---+--------------- 30° S |
| | | | |
| 60° S ---------------+---+--------------- 60° S |
| | | | |
| South Pole (90° S) |
| |
| West Longitude | East Longitude |
| Prime |
| Meridian |
| (0°) |
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Characteristics of Longitude
Unlike parallels of latitude, meridians of longitude are not parallel. They are widest apart at the Equator (about 69 miles apart) and gradually converge as they travel toward the North and South Poles, where they all meet at a single point. Meridians are numbered starting at the Prime Meridian (0 degrees longitude), which passes through the Royal Observatory in Greenwich, England. Longitude values increase eastward up to 180 degrees East and westward up to 180 degrees West.
Longitude and World Time Zones
The Earth completes one full 360-degree rotation on its axis every 24 hours. If you divide 360 degrees by 24 hours, you discover that the Earth rotates exactly 15 degrees of longitude each hour. This mathematical reality forms the basis of global time zones. As you travel westward across every 15 degrees of longitude, local time is one hour earlier; as you travel eastward, local time is one hour later.
Using the Geographic Grid Coordinate System
When latitude lines and longitude lines intersect, they form an invisible grid covering the entire surface of the globe.
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| READING GEOGRAPHIC COORDINATES |
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| Rule 1: Always write Latitude first (North or South of Equator). |
| Rule 2: Always write Longitude second (East or West of Prime Meridian).|
| |
| Example: 30° N, 90° W |
| - First find 30° North of the Equator (Latitude). |
| - Next follow along that parallel until you reach 90° West of the |
| Prime Meridian (Longitude). |
| - Result: You have accurately pinpointed New Orleans, Louisiana! |
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Exercises and Solutions
Exercise 1: Calculating Time Difference Across Meridians. A ship captain at the Prime Meridian (0 degrees longitude) in Greenwich, England, notes that the local solar time is 12:00 noon. A naval officer at a port located at 75 degrees West longitude checks his local clock. Using the rule that the Earth rotates 15 degrees per hour, determine the local solar time at the port and explain whether it is morning or afternoon.
Solution 1: To determine the local solar time at 75 degrees West longitude, divide the total degrees of longitude by 15 degrees per hour: 75 divided by 15 equals 5 hours. Because the port is located west of the Prime Meridian, the Earth's rotation has not yet brought that meridian into alignment with the midday sun; therefore, local time is earlier than the time in Greenwich. Subtracting 5 hours from 12:00 noon results in 7:00 a.m. Thus, when it is noon in Greenwich, it is 7:00 in the morning at 75 degrees West longitude.
Exercise 2: Identifying Hemispheres and Coordinate Quadrants. A meteorologist is tracking a severe tropical hurricane located at coordinates 25 degrees North latitude and 60 degrees West longitude. Identify which two hemispheres this storm is situated in, determine whether it is located in the low, middle, or high latitudes, and explain what ocean it is churning across.
Solution 2: The hurricane located at 25 degrees North and 60 degrees West is situated in the Northern Hemisphere (because its latitude is North of the Equator) and in the Western Hemisphere (because its longitude is West of the Prime Meridian). At 25 degrees North, it is positioned just north of the Tropic of Cancer (23.5 degrees North), placing it in the transition zone between the low tropical latitudes and the lower boundary of the middle temperate latitudes. Geographically, these coordinates place the hurricane squarely in the western North Atlantic Ocean, north of the Caribbean islands and east of the Bahamas.