Chapter 2: The Physical World Questions to examine… What causes the seasons? 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 Solar Energy- energy from the sun 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

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

Chapter 2: The Earth & It’s Physical Systems

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

The Seasons Earth’s tilt causes the changing of 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

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

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

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 events & patterns Global warming could threaten life on our planet

Headlines……… “Why are India's farmers killing themselves?” “Alaskan village votes to relocate over global warming” “Study: Over 90% of Great Barrier Reef suffering from coral bleaching” “Rising sea levels a threat to coastal cities?” “More than 80,000 warned to evacuate in raging California fire”

What Affects Climate? 1. Large Bodies of Water Big bodies of water can affect temperature because water heats and cools slowly –coastal areas experience less temperature change

What Affects Climate? 2. Elevation This mountain is in Africa near the equator. Why is there snow on top of this mountain? Temperatures decrease with elevation

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

What Affects Climate? 3. 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? 4. Ocean Currents Ocean currents move heat around the Earth Ocean Currents- large streams of surface seawater Ocean currents can affect temperatures

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

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

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

Movement of Continents 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…)

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

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

A Fault Near Indy??????

Earth’s Water Supply Water covers around 70% 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 Much freshwater is in form of 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

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

Weathering & Erosion 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

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