World Natural Environments

Introductory concepts Earth-sun relationships Geographic grid Map use

Earth-sun relationship Significance: seasonal distribution of solar radiation general circulation of atmosphere & oceans Spatial distribution of climate regions & vegetation types

Plane of the ecliptic

Axial Inclination

Axial Parallelism

2. Geographic grid Significance: Provides system for locating features Longitude provides basis for time zones

Meridians of Longitude Measures angular distance east or west Reference point is the prime meridian through Greenwich, England Values range from 0 – 180o Longitude is the x in an (x,y) coordinate pair

Parallels of Latitude Measures angular distance north or south Reference point is the equator Values range from 0 – 90o Latitude is the y in an (x,y) coordinate pair

Latitude / Longitude Usually measured in degrees, minutes, seconds (e.g. 90o 30’ 36”) 60 seconds / minute 60 minutes / degree so, 3600 seconds / degree May be expressed in decimal degrees 90o 30’ 36” = 90.51o

(-x, y) (x, y) (-x, -y) (x, -y) Where x = longitude and y = latitude

3. Map use Uses of maps: Aids to location, navigation Portray spatially distributed information

Thematic maps Isopleth maps Choropleth maps:

Isopleth maps Constructed from point data Extrapolated to lines or areas Displays continuous data

Choropleth maps Constructed from area-based data Boundaries of areas may be natural or man-made (defined) Displays discrete data

Exercise 1