© 2014 Pearson Education, Inc. Chapter 2 Lecture McKnight's Physical Geography 11e Lectures Chapter 1 Introduction to Earth © 2014 Pearson Education, Inc. Andrew Mercer Mississippi State University

© 2014 Pearson Education, Inc. Learning Goals of This Chapter Distinguish the key concerns for geographers who study the world. Analyze how geographers use science to explain and understand the natural environment. Identify the four environmental “spheres” of Earth. Illustrate how the concept of Earth systems helps us to understand the interrelationships of the four environmental “spheres” of Earth. Describe Earth’s relationships within the solar system. Compare the size of Earth with the size of its surface features.

© 2014 Pearson Education, Inc. Learning Goals of This Chapter Determine the latitude of a location on Earth. Determine the longitude of a location on Earth. Locate a place given the latitude and longitude coordinates. Explain how latitude and longitude together identify a location on Earth. Summarize the factors that cause the annual change of seasons. Describe the changes in the patterns of sunlight around Earth during the year. Explain how time zones were established.

© 2014 Pearson Education, Inc. Learning Goals of This Chapter Describe how time zones are used to establish actual times around the world. Discuss the relationship between time zones and the international dateline.

© 2014 Pearson Education, Inc. Introduction to Earth Geography and Science Environmental Spheres and Earth Systems Earth and the Solar System The Geographic Grid – Latitude and Longitude Earth–Sun Relations and the Seasons Telling Time

© 2014 Pearson Education, Inc. Geography and Science Definition Sciences that branch from geography Physical versus cultural Summary of global environmental change Globalization – definition and its role in geography

© 2014 Pearson Education, Inc. Geography and Science The scientific method –Observe phenomena –Formulate a hypothesis –Design an experiment to test the hypothesis –Predict the outcome of the experiment –Conduct the experiment –Draw conclusions Scientific “proof” Establishment of scientific theory

© 2014 Pearson Education, Inc. Geography and Science Measurement systems –Need measurement systems to quantify scientific processes –SI versus English units –Conversions

© 2014 Pearson Education, Inc. Geography and Science Unit conversions

© 2014 Pearson Education, Inc. The Environmental Spheres Four primary spheres 1.Lithosphere – “stone” 2.Atmosphere – “air” 3.Hydrosphere – “water” 4.Biosphere – “life” Interactions between the spheres

© 2014 Pearson Education, Inc. The Environmental Spheres Earth systems –Closed systems – those contained from outside influence –Open systems – energy and matter free to be exchanged across systems –Equilibrium – systems are in balance (input = output) –Interconnected systems – change in one system affects another (example of a glacier) –Feedback loops, positive versus negative

© 2014 Pearson Education, Inc. Earth and the Solar System Origins – the big bang Formation of the solar system –Formed 4.5 to 5 billion years ago from a nebula –Eight planets revolve around the Sun in elliptical orbits –Four terrestrial planets –Four gas giants –Earth is the third planet

© 2014 Pearson Education, Inc. Earth and the Solar System The solar system

© 2014 Pearson Education, Inc. Earth and the Solar System Earth’s physical characteristics –Maximum relief –See figure –Imperfect sphere –Equatorial diameter ~ 12,756 km –Polar diameter ~ 12,714 km –Circumference of 40,000 km

© 2014 Pearson Education, Inc. The Geographic Grid – Latitude and Longitude Location on Earth –Need an accurate location on Earth to describe geographic features –Use Earth’s rotation axis to base location on the surface –North Pole and South Pole –Plane of the equator

© 2014 Pearson Education, Inc. The Geographic Grid – Latitude and Longitude Great circles – Circles that bisect a sphere and pass through the sphere’s center – Identify the shortest distance between two points on a sphere—great circle distance – Plane of the equator is a great circle – Small circles

© 2014 Pearson Education, Inc. The Geographic Grid – Latitude and Longitude Graticule Latitudes – Angle north or south of the equator – Parallels – Seven important latitudes – Latitude zones

© 2014 Pearson Education, Inc. The Geographic Grid – Latitude and Longitude Longitudes – Angular description of east–west direction – Meridians – Important longitudes – Convergence at poles Location on the graticule based on latitude and longitude

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons Rotation of the Earth – 24 hours for one rotation – Circular motion at all latitudes but the poles – Rotation is counter-clockwise relative to the North Pole –Converge at the poles –Diurnal transition from light to darkness (circle of illumination) –Tidal effects from the Moon and Sun –Coriolis force

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons Earth’s revolution around Sun –One revolution takes 365 ¼ days –Elliptical orbit –Aphelion (152,100,000 km) –Perihelion (147,100,000 km) –Average distance (149,597,871 km)

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons Orbital Properties –Plane of the ecliptic –Earth’s axis tilted at 23.5° relative to ecliptic Polarity of the Earth’s axis –Parallelism –North Pole always points toward Polaris (“North Star”) Combined effects contribute to seasons

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons Three important conditions –Declination of the Sun –Solar altitude –Length of day – circle of illumination Two solstices –June solstice, date, about June 21th –December solstice, date about December 21th Two equinoxes –March equinox, date about March 20th –September equinox, date, about September 22nd

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons June solstice –Occurs on approximately June 21 each year –Sun directly overhead at 23.5° N latitude –Antarctic Circle in 24 hours of darkness, Arctic Circle in 24 hours of daylight –Marks start of summer in Northern Hemisphere; winter in Southern Hemisphere

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons December solstice –Occurs on approximately December 21 each year –Sun directly overhead at 23.5° S latitude –Arctic Circle in 24 hours of darkness, Antarctic Circle in 24 hours of daylight –Marks start of winter in Northern Hemisphere; summer in Southern Hemisphere

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons Equinoxes –Occur on approximately March 21 and September 21 each year –Day length 12 hours worldwide (“equinox”) –Sun directly overhead at the equator Latitude receiving vertical rays –Varies between the Tropic of Cancer (June solstice) and Tropic of Capricorn (December solstice)

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons Day length –Longest in Northern Hemisphere on June solstice –Opposite in Southern Hemisphere –Arctic and Antarctic day length variations

© 2014 Pearson Education, Inc. Earth–Sun Relations and the Seasons Significance of seasonal patterns –Spread of solar rays over small and large areas –Equator maintains equal days and nights –Tropical latitudes consistently warmer –Polar latitudes consistently cooler –Large seasonal variations in temperature in midlatitudes

© 2014 Pearson Education, Inc. Telling Time Three physical measures of time –Tropical year –Lunar month –Solar day Solar noon –Sun casts the shortest shadow Ante meridian (AM – “before noon”) Post meridian (PM – “after noon”)

© 2014 Pearson Education, Inc. Telling Time Current time system –24 time zones –Greenwich Mean Time (GMT) (also known as Universal Time Coordinated [UTC]) is standard –Controlling meridian for each time zone –Several countries have multiple time zones in their borders –Time zone boundaries subject to local, political, and economic boundaries of different nations –180° meridian the International Date Line

© 2014 Pearson Education, Inc. Telling Time Time zones of the world

© 2014 Pearson Education, Inc. Telling Time Time zones of the United States

© 2014 Pearson Education, Inc. Telling Time Daylight-savings time –Move clocks ahead by an hour during the summer months –Originally done by Germans during WWII; now practiced by many nations –Conserves lighting energy by providing an extra hour of daylight

© 2014 Pearson Education, Inc. Summary Geography is the study of the distribution of physical and cultural attributes of Earth. Many sciences have branched off of geography. The scientific method is important when doing scientific studies. Earth has four primary spheres, the atmosphere, the lithosphere, the hydrosphere, and the atmosphere.

© 2014 Pearson Education, Inc. Summary The solar system formed 5 billion years ago and consists of eight planets. Earth is an imperfect sphere. A latitude and longitude grid helps identify locations on Earth’s surface. Earth rotates on its axis in 24 hours. Earth revolves around the Sun in 365 ¼ days. Tilt of Earth’s axis causes seasons.

© 2014 Pearson Education, Inc. Summary Equinoxes and solstices help identify when a seasonal transition occurs. Time zones were established to have a uniform global time system. Daylight-savings time was devised to conserve energy by adding an hour of daylight.