| heartland theory | sir halford john mackinder's theory that russia is the strategic center of the earth |
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| hemisphere | half of the earth's surface. there are four hemispheres, northern and southern (divided by the equator) and the eastern and Western (divided by the prime meridian and 180°) |
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| humidity | the amount of water vapor in the air |
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| hurricane | a tropical story that contains winds of at least 74 miles per hour (119km/h). also known as a cyclone in the northern indian ocean and a typhoon in the western pacific ocean. |
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| hydrologic cycle | the circulation of water between the atmosphere, streams and land, the ocean, and back to the atmosphere. |
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| hydrosphere | the water of the earth |
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| hypocenter | the point under the earth's surface where the energy of an earthquake is first released. the point directly above the hypocenter on the earth's surface is the epicenter |
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