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The Sun is the driving force behind weather, climate, and convection –Weather changes from day to day. –Climate = a region’s general pattern of weather over a long period of time. • The equator receives the most direct angle of sunlight, creating the warmest climates. 1 of 11 2 of 11 Heating differences causes there to be different air masses. cool air (or water) is more dense than warm, so it sinks, creating currents by convection sun heats land and oceans by radiation land/ocean heats the air above it by conduction 3 of 11 Land-Ocean Interactions Land heats up faster than water (= the ocean). – The air over the land will also heat quickly. – Warm air rises, starting a convection current. – This brings moist ocean air inland. • Ocean air holds a lot of water vapor. • Warm air can also hold more water vapor. – When air cools, it may no longer be able to hold on to all of the water vapor, forming clouds & precipitation. 6 of 11 Air movements create weather changes. Air mass = A body of air that has similar pressure, temperature, & humidity. •Different air mass pressures cause wind. • Air moves from high to low pressure areas. -Generally blow from poles toward equator -Weather often changes when air pressure changes -A front is where two air masses meet or collide 4 of 11 Frontal Systems Symbols Weather Map • Oceans can also influence weather in extreme ways, such as in the formation of hurricanes. = A low pressure tropical storm that forms over ocean water. • Oceans impact climate because they heat and cool slowly (=good insulator!). – Land near the ocean is often warmer in winter and cooler in summer, meaning inland climates differ from those near the ocean at the same latitude. • Oceans also impact climate via currents… 8 of 11 Current – movement of water in the ocean • Surface currents are affected by Winds Continental deflections Coriolis Effect – following the curve of the Earth as it rotates • Deep ocean currents are affected by Temperature differences (density) Salinity differences (density) 9 of 11 Movement of currents is constant and creates a “global conveyor belt” that transfers heat from one part of the Earth to another via water. 10 of 11 Plate Tectonics and Continental Drift Alfred Wegener 1912 - proposed that all the continents were once joined as a single landmass – he called this “supercontinent” Pangaea – stated the continents have separated and collided as they have moved over millions of years – called his theory “continental drift” 12 Plate Tectonics • The Earth’s crust is divided into 12 major plates which are moved in various directions. • This plate motion causes them to collide, pull apart, or scrape against each other. • Each type of interaction causes a characteristic set of Earth structures or “tectonic” features. • The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction. Wegener’s 5 major pieces of Evidence: 1. Continents (esp. South America & Africa) seem to fit together like pieces of a puzzle 2. Matching fossils occur on east coast of S. America & west coast of Africa 3. Matching folded mountain belts on coasts of S. America & Africa 7 Evidence cont… 4. Evidence of ancient climates show landmasses were once located elsewhere - Ex: glaciers in Africa ! 5. Data for latitudes & longitudes of locations is changing 8 The Earth’s Layers cont… • Crust – outermost layer – thinnest layer – the layer we live on – divided into pieces, called tectonic plates – two types: continental and oceanic crust • Mantle – thickest layer – “flows” and allows the tectonic plates to move on top – primarily magma 16 The Crust • This is where we live! • The Earth’s crust is made of: Continental Crust Oceanic Crust - thick (10-70km) - buoyant (less dense than oceanic crust) - mostly old - thin (~7 km) - dense (sinks under continental crust) - young Plate Movement • “Plates” of lithosphere are moved around by the underlying hot mantle convection cells Three Types of Plate Boundaries • Divergent • Convergent • Transform http://www.learner.org/interactives/dynamicearth/plate.html Divergent Boundaries • Spreading ridges – As plates move apart new material is erupted to fill the gap Convergent Boundaries • There are three styles of convergent plate boundaries – Continent-continent collision – Continent-oceanic crust collision – Ocean-ocean collision Continent-Oceanic Crust Collision • Called SUBDUCTION example..Andes Mountains Continent-Continent Collision • Forms mountains, e.g. European Alps, Himalayas Ocean-Ocean Plate Collision • Island arcs and deep oceanic trenches..Japan Mariana Trench Plate Tectonics Summary • The Earth is made up of 3 main layers (core, mantle, crust) • On the surface of the Earth are tectonic plates that slowly move around the globe • Plates are made of crust and upper mantle (lithosphere) • There are 2 types of plates • There are 3 types of plate boundaries • Volcanoes and Earthquakes are closely linked to the margins of the tectonic plates TOPO MAPS • A topographic map is a two dimensional representation of three dimensional space. • Utilizes contour lines to show elevation. • Contour lines are lines of equal elevation. • Elevation is distance above sea level. • A contour line connects points of the same elevation • If you walked around an entire mountain staying on the same contour line, you wouldn’t change elevation. Index contours • If we wrote the elevation of every contour line on that line, then our map would be covered in numbers. • Instead, we use index contour lines. 1. Usually darker lines 2. Have the elevation marked on them Index contours Rules for Contour Lines • Contour lines always close to form an irregular circle, it’s just that sometimes you can’t see the complete thing. • Contour lines will make a ‘v’ in the upstream direction a of a stream. Rules for Contour Lines What is the contour interval This entire line represents 1200 feet above sea level. Rules for Contour Lines Contour lines NEVER, EVER cross What’s going on?? Is this area above or below 1200 feet? ? What does contour line spacing indicate? The closer together the contour lines are, the steeper the hill is. The more spread apart they are, the gentler the slope. Traveling along the red line would be much steeper than traveling along the green line. Weathering and Erosion Topo maps show changes over time to the Earth’s surface caused by weathering and erosion Weathering is the breakdown and alteration of rocks and minerals at or near the Earth's surface Erosion • Erosion is the wearing away of land or soil by the action of wind, water, or ice. http://www.ars.usda.gov/is/graphics/photos/k5951-1.htm