Biogeography 316 Week 1 : 8/28 & 8/30
Objective: To review basic geographic and astronomical processes important in understanding biogeography
Lecture Outline
I. Earth as a Sphere
a. earth size/ shape
b. meridians/parallels
c. latitude/longitude
II. Earth as a rotating sphere
a. earth's rotation
b. effects of rotation
III. Earth as Revolving sphere
a. axial tilt
b. perihelion/aphelion
c. solstice and equinoxes
IV. Global exercise: declination of the sun
Earth shape: round?
"Oblate ellipsoid"
Diameter: 12,756 km (7926 miles)
Length at the poles: 12,714 (7900 miles)
Circumference: 40,075 km (24,900 miles)
roughly 40,000 km (25,000 miles)
Distance to sun: 150 million km (93 million miles)
Great circle
small circles
Meridians/Parallels
Meridians: north/south lines
connecting the poles
Parallels:east/west lines running
parallel to each other
Longitude: lines going north and south 0-180° E/W of prime meridian
Latitude: Lines going east and west 0-90° N/S of the equator
II. Earth as a Rotating Sphere
How do we know the earth rotates?
Revolution
|The earth revolves around the sun: 365.25 days
In a counterclockwise motion when viewed from space. The orbit is
elliptical.
Tropical year:from vernal equinox to vernal equinox
Axial tilt: 23 1/2°
Orbit: Perihelion: closest to the sun (~Jan 3)
Aphelion: Farthest from the sun (~July 4)
Equinox: means "equal night", 12hrs day/night
March 20/21: Vernal equinox
Sept 22/23: Autumnal equinox
Solstices:
June 21/22: Summer solstice
Dec. 21/22: Winter Solstice
Solar Noon (Declination of the sun): know where you are, know where the sun is directly overhead. See handout for calculation.
Declination of the Sun Assignment
SFSU Page SFSU Geography Department Biogeography 316 Professor Barbara Holzman's Home Page