Alexander von Humboldt I shall endeavor to find out how natures forces act upon one another, and in what manner the geographic environment exerts its influence on animals and plants. In short, I must find out about the harmony in nature.
Review Today, most geographers consider themselves to be a human (cultural) or physical (environmental) specialists. Within these two broad fields are a range of subfields which overlap.
Review Physical Geography – Disciplinary Connections and Overlaps Geomorphology Geology Hydrology Meteorology Climatology Oceanography Source: Andrews, Gavin J. Linehan, Denis "Geography." Encyclopedia of Environment and Society. 2007. SAGE Publications. 22 Aug. 2011.
Science and Geography Knowledge in physical geography is advanced through the study of science. – Processes and patterns – Observation and measurable data – International System of measurement (SI) and the traditional (or English) system.
Science and Geography Man cannot have an effect on nature, cannot adopt any of her forces, if he does not know the natural laws in terms of measurement and numerical relations. Alexander Von Humboldt
Science and Geography Measurement Systems – Need measurement systems to quantify scientific processes – SI versus English units – Conversions
The Environmental Spheres Earth’s surface is a complex interface where four spheres meet and, to some degree, overlap and interact. These four spheres provide important organizing concepts for the systematic study of Earth’s physical geography.
The Environmental Spheres 1 Four primary spheres 4 2 3 1. atmosphere—“air” 2. lithosphere—“stone” 3. hydrosphere—“water” 4. biosphere—“life” Interactions between the spheres
Pause and Reflect Which of the environmental spheres do you think humans have altered the most? Which have humans altered the least?
Earth’s True Shape The Earth is not a perfect sphere. The true shape of the Earth called an Oblate Spheroid. – The term "Oblate" refers to its slightly oblong appearance. – The term "Spheroid" means that it is almost a sphere, but not quite. – The Earths shape is only very slightly oblate.
Earth’s True Shape Because of its rotation, the Earth bunches up in the middle. This "middle" is the equator.
The Geographic Grid 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—halfway between poles and perpendicular to Earth’s surface
The Geographic Grid (a) Parallels of latitude divide the globe crosswise into rings. (b) Meridians of longitude divide the globe from pole to pole.
The Geographic Grid Latitude – Angle north or south of the equator – 7 important latitudes: – Tropic of Cancer and Capricorn (23.5° N and S) – Equator (0°) – Poles (90° N and S) – Arctic and Antarctic Circles (66.5° N and S) – Parallel An imaginary line that connects all points of the same latitude
The Geographic Grid Longitude – Lines of longitude are known as meridians. – Prime Meridian (0° longitude) located at Greenwich, England – Angle east or west of the Prime Meridian – Converge at the poles
The Geographic Grid Longitude – Meridians Not parallel to each other, except where they cross at the equator, where they are also the furthest apart. They are close together northward and southward, converging at the poles. Locations east of the prime meridian are described in degrees east longitude. Locations west of the prime meridian are described in degrees west longitude.
The Geographic Grid Globes – Parallels and meridians are typically marked on globes in 10° or 15° increments. 10 – If the parallels are meridians are not marked on the globe, latitude and longitude are determined by using the degree markings on the arms or rings supporting the globe.
Great Circles and Small Circles GreatCircles are the largest circle that can be drawn on a sphere. – Must pass through the center of the sphere; – Represents the circumference and divides the surface into two equal halves or hemispheres.
Great Circles and Small Circles Great Circles – Circles which bisect a sphere and pass through the sphere’s center – Identify the shortest distance between two points on a sphere—great circle distance
Earth–Sun Relations Do you know like we were saying, about the earth revolving? Its like when youre a kid, the first time they tell you that the world is turning and you just cant quite believe it cause everything looks like its standing still. Doctor Who
Doctor Who I can feel it . . . the turn of the earth. The ground beneath our feet is spinning at a thousand miles an hour. The entire planet is hurtling around the sun at sixty seven thousand miles an hour. And I can feel it. Were falling through space, you and me, clinging to the skin of this tiny little world. Doctor Who
Earth–Sun Relations The functional relationship between Earth and the Sun is vital because life on Earth is dependent on solar energy. Two basic Earth movements are critical: – Earth’s daily rotation on its axis. – Earth’s annual revolution around the Sun.
Earth-Sun Relations Rotation of the Earth – 24 hours for one rotation – Circular motion at all latitudes but the poles – Rotation is counterclockwise relative to the North Pole – Converge at the poles – Daily transition from light to darkness
Earth-Sun Relations The direction of rotation of the Earth can be thought of as (a) counterclockwise at the north pole, or (b) from left to right (eastward) at the equator.
The Annual March of the Seasons June solstice – Occurs on approximately June 22 each year – Sun is directly overhead at 23.5° N latitude – Antarctic Circle in 24 hours of darkness – Marks start of summer in Northern Hemisphere; winter in Southern Hemisphere
The Annual March of the Seasons December solstice – Occurs on approximately December 22 each year – Sun is directly overhead at 23.5° S latitude – Arctic Circle in 24 hours of darkness – Marks start of winter in Northern Hemisphere; summer in Southern Hemisphere
The Annual March of the Seasons Equinoxes – Occur on approximately March 21 and September 21 each year – Day length is 12 hours worldwide (“equinox”) – Sun is directly overhead at the equator
The Annual March of the Seasons Day length – Always 12 hours at the equator – In the Northern Hemisphere, day length increases after March equinox – Maximum day length during June solstice in Northern Hemisphere – Opposite for Southern Hemisphere
The Annual March of the Seasons Significance of seasonal patterns – Spread of solar rays over small and large areas – Tropical latitudes consistently warmer – Polar latitudes consistently cooler – Large seasonal variations in temperature in midlatitudes
Telling Time Current time system – 24 time zones – Greenwich Mean Time (GMT) 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 chosen as the International Date Line