Chapter 2: The Physical World Questions to examine… What causes the seasons? What does our planet consist of? What affects our climate (weather)? How is our Earth’s land constantly changing? How does the Earth’s water supply work?

Day 1 – The Earth – Sun Relationship

Our Star All life on Earth requires solar energy to survive Solar Energy- energy from the sun (plants and animals require the sun’s light and heat energy to survive)

The Sun’s Rotation 24 hrs. = one complete rotation Rotation causes day & night Rotation- one complete spin of Earth on its axis (Does it look like the sun moves? Does it move?) NO! THE EARTH MOVES!

Revolution Revolution- Earth’s trip around the sun One revolution takes 365 ¼ days – 1 year

Tilt Tilted toward the sun, weather is warmer Tilted away from the sun, weather is colder Nearer you are to the equator, the more intense the sunlight

The Tropics Tropics – regions close to the equator, hot - experience seasons based on rainfall, wet & dry seasons

The Seasons The seasons are opposite in northern/southern hemispheres Earth tilted away from sun = winter for us Earth tilted toward sun = summer for us Earth’s tilt causes the changing of the seasons! December in Australia

Sun and Location Review….. Earth’s tilt causes the seasons Earth’s shape affects the amount of sunlight places get too Higher latitudes – cooler Lower latitudes – warmer

Day 2 – The Earth & It’s Physical Systems

Layers of the Earth Earth has layers (think onion) 3 main layers –Crust (thin) –Mantle (thick) –Core (solid inner & liquid outer)

Earth’s 4 Spheres Hydrosphere – 70% of Earth is water Lithosphere – 30% of Earth is land Atmosphere – air we breathe (gases) Biosphere – all living things on Earth

Weather & Climate “What is it like outside today?” Weather- Short-term changes in the air for a given place and time “What is it usually like outside for this time of year?” Climate- a region’s average weather conditions over a long period

What Affects Climate? Large Bodies of Water Big bodies of water can affect temperature because water heats and cools slowly –coastal areas experience less temperature change

Day 3 - Climates

What Affects Climate? Elevation This mountain is in Africa. It is hot in Africa. Why is there snow on top of this mountain? Temperatures decrease with elevation

What Affects Climate? Global Winds Prevailing winds- winds that blow in the same direction over large areas of Earth Winds can make a region warmer or colder (depending on where they come from)

What Affects Climate? Ocean Currents Ocean currents move heat around the Earth Ocean Currents- large streams of surface seawater Ocean currents can affect temperatures

Mountains & Rain Shadows Mountains also create wet and dry areas One side can get a bunch of rain & leave little for the other side. Rain Shadow Effect

Climate Zones 6 Basic Climate Zones: –Tropical : hot, rainy, dense jungle –Desert : very dry, hot or cold –Humid Temperate : changing seasons –Cold Temperate : very short summer, cool –High Mountain : mountain tops, cool/windy –Polar : very cold, ice and snow

Climate Change??? Many scientists believe climates are changing due to human activity… –Increase in Earth’s average temperature –Increase in chemical pollution in air & water –Rising ocean levels –Erratic/violent weather evens & patterns Global warming could threaten life on our planet

Day 4 – Forces Shaping the Earth

Continents- large landmasses that are part of the Earth’s crust Continents

Plate Tectonics- the theory that Earth’s surface is divided into a dozen or so slow- moving plates or pieces of Earth’s crust Plate Tectonics

All of these plates move Pressure below Earth’s surface causes plates to move a couple inches per year Earth’s Plates

 Alfred Wegener - stated that all of the continents were once one supercontinent - PANGEA  Over millions of years the continents shifted to their current positions THEORY OF CONTINENTAL DRIFT (Other scientists told Al he was crazy…) Movement of Continents

Collision of plates creates different landforms like ocean trenches & mountains (Examples: -Marianas Trench -Andes Mountains -Himalaya Mountains) Plates Collide

When plates separate the gap allows magma to reach earth’s surface As lava cools it builds an underwater mountain, can create islands (Ex.: Hawaii) Plates Separate

Earthquakes- sudden, violent movements of Earth’s crust Plates Slide

A Fault Near Indy??????

Weathering- process by which rock is broken down into smaller pieces Ice, roots, and heat can weather rocks Erosion- movement of sediment from one location to another Caused by glaciers, wind, water, and ice Weathering & Erosion

Day 5: Earth’s Land and Water

Landforms- shapes on the planet’s surface Ex. – mountains, valleys, plains, islands, etc. Landforms

Earth’s Water Supply Water covers around 2/3 of the earth Most important resource on earth

Salt Water 97% of Earth’s water is salt water Salt water is unsafe to drink (The Great Salt Lake in Utah is salt water, oceans are salt water)

Freshwater Freshwater- water without salt Makes up 3% of water supply Most freshwater is in glaciers Glaciers- large areas of slow moving ice

More Freshwater Surface water- is found in Earth’s streams, rivers, and lakes Water in streams, rivers, and lakes comes from precipitation Precipitation- rain, snow, sleet, hail

More Freshwater Most of Earth’s available fresh water is underground Groundwater- water found below Earth’s surface (You get groundwater through a spring or well)

The Water Cycle Water is the only thing on Earth that naturally occurs as a liquid, solid, and gas Water cycle- movement of water from Earth’s surface to the atmosphere and back Water cycle is not made or destroyed—it only changes form

1. Evaporation 2. Condensation 3. Precipitation 4. Run-off

Water Problems Lack of freshwater Polluted water Flooding Water shortages due to droughts

Water’s Benefits Water provides us with… Food Recreation Power