Changes on the Earth’s Surface

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 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