Planet Earth http youtu bev Na Xx XNFOj
Planet Earth http: //youtu. be/v. Na. Xx. XNFOj. M Chapter Two
The Earth and the Sun’s Energy • All life on Earth requires solar energy, or energy from the sun, to survive • Amount of solar energy received changes constantly • Earth’s rotation, revolution, tilt, and latitude all affect the amount of solar energy Earth receives
Rotation • Earth spins on its axis-an imaginary line that runs through the center of the planet around which it turns • It takes 24 hours to make one rotation, or complete spin on its axis • As earth spins, different parts of the planet face the sun, causing the changes from day to night
Revolution • Earth follows an orbit or path around the sun • Orbit is not a perfect circle • It takes 365 ¼ days to complete one revolution, or trip around the sun • Our calendar is based on the time it takes Earth to complete its orbit • http: //youtu. be/Ja. G 70 c. J 8 v. DE – Stop at 1: 53
Tilt • Earths axis is tilted at an angle of 23 ½ degrees from vertical • At any given time on Earth, some places on Earth tilt toward the sun, and others tilt away • Places tilting toward the sun receive more solar energy and have warmer temperatures than those that tilt away
Latitude • Latitude is the distance north or south of the Earth’s equator • Low-latitude areas, those nearest to the equator, receive direct rays from the sun all year • High-latitude areas, those farther from the equator, receive indirect rays from the sun and have colder temperatures
Seasons • Earth’s seasons are caused the planets tilt • Many places experience four seasons – Winter, spring, summer, fall • In some parts of the world, seasons are based on the amount of rainfall
Seasons Winter and Summer • Earth tilts away from the sun in the winter and towards it in the summer • Because of the Earth’s tilt, the Northern and Southern hemispheres experience opposite seasons Spring and Fall • In spring, Earth begins to tilt toward sun, solar energy increases, temperatures rise, and days grow longer • In fall, the opposite occurs
Rainfall and the seasons • In the tropics, regions close to the equator, seasons are marked by rainfall rather than temperature • At certain times of the year, winds bring either dry or moist air to the tropics, creating wet and dry seasons
Water on Earth • There are two types of water on Earth. What are they?
Earth’s Water covers 2/3 of the planet • Salt Water About 97% of the Earth’s water – Unsafe to drink because of high salt levels – In general, found in the Earth’s oceans, which cover about 71% of the Earth’s surface – Also found in some of Earth’s lakes
Freshwater • Water without salt • Makes up only 3% of the water supply • Much freshwater locked in glaciers, large areas of slow moving ice, and in the ice of the Arctic and Antarctic regions • Surface water is found in streams, rivers, and lakes – Less than 1% of the Earth’s water supply
Freshwater • Precipitation: water that falls to the Earth as rain, snow, sleet, or hail – Streams form when precipitation collects in narrow channels and flows toward the ocean • Most available freshwater is groundwater, water found below the Earth’s surface – Some naturally bubbles from the ground to the surface as a spring – Most obtained by digging wells
Water Cycle • Water circulates from the Earth’s surface to the atmosphere and back again • It is driven by the sun’s energy • Water is the only substance on Earth that occurs naturally as a solid, a liquid, and a gas, or water vapor • http: //youtu. be/Ysw. L 4 d. IDQuk
Water Cycle • Evaporation: water turns from liquid to gas • Condensation: rising gas cools and condenses, or changes from a vapor into tiny liquid droplets, to form clouds • Precipitation: if the droplets in the clouds become heavy enough, they fall back to the Earth as rain, snow, sleet, or hail • Runoff: excess water that isn’t absorbed as groundwater flows over land collects in streams, rivers, and oceans
The Role of Water in Our Lives Water Problems • Lack of available freshwater – Caused by droughts or overuse • Contaminated, or polluted, water can harm humans, plants, and animals • Flooding can damage property and threaten lives Water Benefits • Provides us with food to eat • Important source of energy • Provides us with recreation, including, swimming, fishing, surfing, and sailing
Earth’s Landforms • Landforms: shapes on the planet’s surface, make up the landscapes that surround us • Mountains: land that rises higher than 2000 feet • Valleys: areas of low land located between mountains or hills • Plains: stretches of mostly flat land • Islands: areas of land completely surrounded by water • Peninsulas: land surrounded by water on three sides
Earth’s Plates • The planet’s continents, or large landmasses, are part of the Earth’s crust: the solid outer layer of the planet • Theory of plate tectonics: The Earth’s surface is divided into a dozen or so slow-moving plates, or pieces of the Earth’s crust
Movement of Continents • Continental Drift: The idea that continents have traveled great distances over millions of years • Theory, developed by Alfred Wegener, states that continents were once united in a single supercontinent and over time, slowly separated and moved to their present positions • As plates collide, separate, and slide, they shape the Earth’s landforms
Plate Movement • Group activity, pages 37 -38 – Define the term. Be sure to describe the cause and effect. – Provide a visual graphic. Be able to draw and explain. – Provide examples • Plates Collide • Plates Separate • Plates Slide
Forces on the Earth’s Surface • Weather, water, and other forces change Earth’s landforms by wearing them away or reshaping them • Weathering: Process by which rock is broken down into smaller pieces called sediment – Heating and cooling can cause rock to crack – Expansion as rocks freeze can cause cracks to expand – Roots of trees can pry rocks apart • Erosion: movement of sediment from one location to another – Can wear away or build up landforms
Types of Erosion • Wind Erosion lifts sediment into the air and can carry it great distances • On beaches and in deserts, deposits can cause dunes • Blowing sand can wear down rock
• Glacial Erosion • Glaciers, or large slow moving sheets of ice, erode the land, by carving valleys and mountain peaks • Crush rock into sediment and move it great distances
• Water Erosion • Waves and flowing water can cut through rock, carry sediment, and deposit sediment in new locations • Floodplains are created when rivers flood their banks and deposit sediment • Sediment carried all the way to the sea creates a delta
Landforms Influence Life Where people settle What jobs are available Language People sometimes change landforms to suit their needs • Examples • •
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