UNIT 1 EARTH DIMENSIONS DETERMINING THE SIZE AND

UNIT 1: EARTH DIMENSIONS DETERMINING THE SIZE AND SHAPE OF EARTH

WHAT’S OUR MODEL OF EARTH? �MODEL S REPRESENT VERY BIG OR SMALL OBJECTS �SIZE AND PROPORTION ARE IMPORTANT �DIFFERENT TYPES OF MODELS: � PHYSICAL � MECHANICAL (MOVING PARTS) � GRAPHIC (MAPS) � MATH (D=M/V)

EVIDENCE FOR EARTH'S SHAPE 2000 YEARS AGO PHILOSOPHERS FIGURED OUT THE EARTH IS A SPHERE OBSERVATIONS AND THEN INFERENCES!

SHIPS ON THE HORIZON �PEOPLE WATCHED SHIPS SAIL AWAY. . . OBSERVATIONS! �GRADUALLY DISAPPEARED WITH THE MAST AS THE LAST VISIBLE PART, AND THE FIRST PART TO REAPPEAR UPON RETURN. . . THEN INFERRED THE EARTH IS A SPHERE

LUNAR ECLIPSE �SHOWS EARTH’S SHADOW, A CURVED ROUNDED SHAPE �OBSERVATIONS AND INFERENCES

ALTITUDE OF POLARIS �POLARIS IS THE NORTH STAR �LOCATED DIRECTLY OVER THE NORTH POLE �THE ALTITUDE OF POLARIS CHANGES AS YOUR LATITUDE CHANGES… TRAVELING NORTH OR SOUTH �FOR ANY LOCATION IN THE NORTHERN HEMISPHERE: �THE ALTITUDE OF POLARIS = YOUR LATITUDE

ALTITUDE OF POLARIS = LATITUDE

THE BEST EVIDENCE FOR EARTH’S SHAPE? �PHOTOS FROM SPACE !

SO WHAT IS EARTH’S SHAPE? �AN OBLATE SPHEROID �EARTH BULGES AT THE EQUATOR �IN CIRCUMFERENCE AND DIAMETER

CAN YOU SEE THE BULGE? �NO! �NOT IN PHOTOS FROM SPACE �NOT IN SCALED DRAWINGS �NOT ON SCALED MODELS �ONLY THROUGH PRECISE MEASUREMENTS DO WE KNOW THE CIRCUMFERENCE AROUND THE EQUATOR IS 68 KM GREATER THAN AROUND THE POLES

SO WHAT’S EARTH’S STRUCTURE? THE LITHOSPHERE. . . SOLID ROCKY PART OF EARTH HYDROSPHERE. . . THE WATER, COVERING 75% OF EARTH ATMOSPHERE. . . THE AIR AND BEYOND TO SPACE BIOSPHERE. . . THE LIFE ON EARTH!

LITHOSPHERE �THE SOLID OUTER SHELL OF EARTH �REFERS TO THE EARTH’S CRUST AND UPPER MANTLE � INCLUDES SOIL AND ROCK OF EARTH’S SURFACE � CRUST � THICKEST BENEATH CONTINENTS � THINNEST BENEATH THE OCEANS � MANTLE IS LAYERED

LAYERS BELOW THE CRUST: �MANTLE �RIGID UPPER MANTLE - SOLID BUT NOT BRITTLE �ASTHENOSPHERE- “PLASTIC-LIKE” �OUTER CORE �HOT MOLTEN IRON �INNER CORE �SOLID IRON AND NICKEL

HYDROSPHERE. . . WATER! �THIN LAYER ON THE LITHOSPHERE �OCEANS, RIVERS, ICE CAPS AND SUBSURFACE WATER �COVERS NEARLY 75% OF EARTH’S SURFACE �OCEANS ACCOUNT FOR 97% �FRESH WATER IS PRECIOUS !

ATMOSPHERE. . . A GAS ! �MULTIPLE LAYERS �EXTENDS SEVERAL HUNDRED KILOMETERS TO SPACE �PRIMARILY NITROGEN AND OXYGEN

LOCATING POSITIONS ON EARTH WHAT’S YOUR GLOBAL ADDRESS?

LOCATING POSITIONS ON EARTH �USE A COORDINATE SYSTEM � A GRID OF IMAGINARY LINES �LATITUDE AND LONGITUDE

LINES OF LATITUDE �EQUATOR IS 0° �DIVIDES EARTH INTO NORTHERN/SOUTHERN HEMISPHERES THE POLES ARE 90° NORTH AND SOUTH �PARALLELS �RUN EAST-WEST �MEASURE DISTANCE NORTH OR SOUTH OF EQUATOR �NEVER INTERSECT

LINES OF LONGITUDE �PRIME MERIDIAN IS 0° �INTERNATIONAL DATELINE IS 180° �MERIDIANS RUN NORTH/SOUTH �DO INTERSECT. . . AT THE POLES

LATITUDE AND LONGITUDE �MEASURED IN DEGREES °, MINUTES ‘ AND SECONDS” �BASED ON ANGLES OF THE SUN, STARS AND EARTH‘S ROTATION �LATITUDE MEASURES FROM THE EQUATOR TO THE POLES. . . 0° TO 90° NORTH/SOUTH �LONGITUDE MEASURES FROM THE PRIME MERIDIAN TO THE INTERNATIONAL DATELINE. . . 0° TO 180° EAST/WEST

TIME ZONES �RELATE LONGITUDE AND EARTH’S ROTATION, FROM WEST TO EAST �ALL TIME IS MEASURED IN RELATION TO THE PRIME MERIDIAN IN GREENWICH ENGLAND (0°) �EVERY 15° OF LONGITUDE = 1 HOUR OF TIME �AS YOU TRAVEL WEST, IT’S EARLIER IN THE DAY COMPARED TO THE PRIME MERIDIAN �AS YOU TRAVEL EAST, IT’S LATER IN THE DAY

TIME ZONES, LONGITUDE AND EARTH’S ROTATION. . . HUH? �EARTH ROTATES WEST TO EAST �ROTATES ONCE IN 24 HOURS � 360°÷ 24 HOURS = 15°/HOUR �EVERY 15° OF LONGITUDE = 1 HOUR OF TIME �EXAMPLE: 5 HOURS DIFFERENCE IN TIME ZONES 5 HOURS X 15° = 75° DIFFERENCE IN LONGITUDE

HOW CHARACTERISTICS OF A LOCATION ARE DESCRIBED MEASURABLE “FIELDS”

“FIELDS” ARE REGIONS OF SPACE WITH MEASURABLE QUANTITIES �AIR TEMPERATURE �WIND SPEED �HUMIDITY �WATER DEPTH �AIR PRESSURE �WATER TEMPERATURE �SNOW DEPTH �VOLCANIC ASH �RAINFALL �WATER /AIR POLLUTION

MEASURED FIELD VALUES ARE MAPPED �ISOLINES CONNECT POINTS ON A MAP THAT HAVE THE SAME VALUE OR MEASUREMENT �ISOLINES NEVER INTERSECT! EXAMPLES: �ISOTHERMS - EQUAL TEMPERATURE �ISOBARS - EQUAL AIR PRESSURE �CONTOUR LINES - SAME ELEVATION

GRADIENT SHOWS THE CHANGE IN “FIELD VALUE” BETWEEN TWO PLACES �GRADIENT DESCRIBES SLOPE �EXAMPLES: �SKI SLOPE �ROOF PITCH �WHEELCHAIR RAMP �DRAIN AGE PIPE

GRADIENT EXAMPLE: STREAM FLOWS DOWNHILL LOCATION X IS 5 MILES FROM LOCATION Y. THE ELEVATION DIFFERENCE BETWEEN BOTH LOCATIONS IS 200 FEET. STREAM GRADIENT = 200 FEET 5 MILES GRADIENT = 40 FT. /MILE

TOPOGRAPHIC MAPS �SHOW LANDFORM FEATURES LIKE LAKES, RIVERS AND HILLS �SCALE PROVIDES DISTANCE MEASUREMENT �SYMBOLS AND COLORS REPRESENT FEATURES �BUILDINGS RAILROADS �TRAILS �SWAMPS

TOPOGRAPHY / ELEVATION CHANGES �CONTOUR LINES SHOW CHANGES IN ELEVATION �CONTOUR INTERVAL IS THE ELEVATION DIFFERENCE FROM ONE LINE TO THE NEXT

CONTOUR LINE GRADIENT �WHEN LINES ARE CLOSE TOGETHER, THE SLOPE IS STEEP �WHEN LINES ARE FAR APART, THERE IS MINIMAL SLOPE

CREATING A TOPOGRAPHIC PROFILE: A SIDE VIEW �LINE A TO B �MARK EACH CONTOUR LINE ALONG LINE AB �CREATE A VERTICAL GRAPH OF THE TOPOGRAPHIC CHANGES

LET’S SEE HOW WE DO. . . �WHAT’S THE CONTOUR INTERVAL? �WHAT LANDFORMS ARE ON THIS MAP? �IS ONE AREA STEEPER? �HOW WOULD YOU MAKE A PROFILE?

DRAWING ISOLINES �REMEMBER, ISOLINES NEVER INTERSECT �ISOLINES RUN TO THE EDGE OF THE MAP. . . DON’T LEAVE THEM “DANGLING” �NOT ALL POINTS ON A MAP NEED TO BE CONNECTED BY AN ISOLINE