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geog lecture 2

# geog lecture 2 - LATITUDE LONGITUDE Earth is a sphere or...

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LATITUDE & LONGITUDE Earth is a sphere or has a spheroidal shape. It is a little "squished" at the poles or has what is called a geoidal bulge at the equator. Equatorial diameter: 12, 756 km = 7926 mi (24,902 mi circumference) Polar diameter: 12, 714 km = 7900 mi (24,860 mi cir.) To Locate Places on the surface we use a grid system. Several types have been developed and are in use. Most common or well known is the latitude and longitude grid system . Latitude : parallel lines that run east/west, measured north/south 90 degrees max, 0-90 Athens = 44 N Longitude : non-parallel lines that run north/south, measured east/west start at 0, end at 180 (international date line) prime meridian – Greenwich England. *map makers used to use their own prime meridian, international dateline zigzags around countries so that they’re not on different days ** degree: one part of a circle, with 360 parts or degrees in a complete circle a degree is divided into 60 equal parts or minutes a minute is divided into 60 parts, or seconds EX: 12°35'15" N 104°55'30" E > only two that don’t require north and south, 0,0 and 0,180. (only one 180) latitude – put N/S on it, longitude - put E/W on it Parallels of Latitude are about 111 km (69 mi) apart no matter which two you pick.

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Meridians of Longitude are 111 km (69 mi) apart only at the equator . tropic of cancer ---23.5 N, Capricorn – 23.5 S, arctic circle – 66.5 N, Antarctic 66.5 S IDL 180, prime meridian 0 the tripcs – between cancer and Capricorn MAP PROJECTIONS * the problems of transferring a round globe onto a flat surface, a piece of paper * do this by an orderly arrangement of parallels & meridians * several primary types or methods: * cylindrical * Mercator (one of the most common types used) Greenland looks bigger than south africa * conic * planar * equal-area * polar * gnomonic * the matter of Scale of a map: the ratio of distance on the map to actual distance on the ground EX: 1:24000 means, 1 inch on the map equals 24,000 inches on the ground or 2000 feet; 1:100000 -----> 1 inch on the map equals 1 million inches on the ground, or about 83,333.33 feet or about 15.78 miles;
EARTH/SUN RELATIONSHIPS ** > 99% of Earth's energy is from the sun * these variations cause an unequal heating of the Earth surface which drives the ocean currents and creates wind, transporting energy across the globe Earth Movements Rotation: the spinning of the earth about its axis * 1 turn every 24 hours; defines day & night * Earth turns at different rotational velocity for each degree of latitude; * turns counterclockwise, when viewed from above the North Pole * earth turns at different rotational velocity fore * moves at 66,000 mph. Revolution: movement of the earth in its orbit around the sun * 1 orbit every 365.2422 days = 1 year (365 days, 5.8 hours) * moves at ~ 66,660 mph ast it travels around the sun * counterclockwise orbit, when viewed from above North Pole * orbit is elliptical, so at one time of year it is closer to the sun than another * perihelion: closest to the sun, 1.47 x 10^8 km, (91,500,000 mi) jan 3 rd or 4e * aphelion: 1.52 x 10^8km (94,500,000), furthest from the sun, july 3-4

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Earth's Seasons partially due to rotation but moreso revolution
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