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Changes on the Earth’s Surface. Earth. Rotation spins on axis Axis runs through North and South Poles Revolution Orbits the Sun 365.24 days Leap Year Tilt Axis is tilted 23.5 degrees. Latitudinal Regions. Tropics Warm, low-latitude areas (near equator) Polar regions
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Earth • Rotation • spins on axis • Axis runs through North and South Poles • Revolution • Orbits the Sun • 365.24 days • Leap Year • Tilt • Axis is tilted 23.5 degrees
Latitudinal Regions • Tropics • Warm, low-latitude areas (near equator) • Polar regions • Cold, high-latitude areas (near poles) • Middle latitudes • Areas between tropics and polar regions
Seasons • Because the Earth tilts, the angle of the Sun’s rays vary throughout the year. • Direct rays = warmer • Indirect rays = cooler • This is why we have seasons!
Types of Seasons • Temperature-based • Spring, Summer, Fall, Winter • Precipitation-based • Wet, Dry
Solstices and Equinoxes • Solstice • Earth’s poles point at their greatest angle toward or away from the Sun • 21 December and 21 June • Equinox • equi = equal nox = night • Poles are at 90 degree angle to the Sun • 21 March and 22 September
Solstices • December Solstice • North Pole points away from Sun • Sun strikes Tropic of Capricorn directly • 24 hours of daylight in Antarctic Circle • June Solstice • South Pole points away from Sun • Sun strikes Tropic of Cancer directly • 24 hours of daylight in Arctic Circle
Weathering • Process by which rocks break and decay over time • Chemical Weathering • Substances or chemicals in the air dissolve rock • Mechanical Weathering • Physical processes • Deserts – heating and cooling • Mountains – freezing and thawing • Tree roots • Sediment • Smaller particles of gravel, sand, and mud
Erosion • Movement of surface material from one location to another • Caused by water, wind, and ice
Water Erosion • Most important force of erosion • Rapid erosion • Rainfall washes out areas with few points • Water erosion • Channels of water cut into the earth • Wave erosion • Changing shorelines
Wind Erosion • Abrasion • Blasts sand particles against rock • Displacement • Blows sand and dust to new location • Sand dunes • Loess • Fine-grained, windblown soil • Very fertile
Ice Erosion • Glaciers • Thick mass of ice • Erode rock and move sediment • Moraine • Accumulation of rock and soil from glacial erosion
I don’t know how this fits into this lesson… • Acid rain • Chemicals in air pollution combine with water in air • Produces a mild acid • Can damage trees and kill fish in lakes