PHYSICAL

GEOGRAPHY

By Brett Lucas

INTRODUCTION

Introduction to Earth

Geography as a Field of Learning

Geography is from two Greek words, “Geo” – Earth, and “Graphien” – to write.

Elements/Branches of Geography – Physical & Human or Cultural (see next slide). This class is concerned with Physical Geography.

Elements of Geography

Introduction to Earth

Environmental Spheres (next slide)

The Solar System

Size and Shape of Earth

The Geographic Grid

Earth Movements

Annual March of the Seasons

Telling Time

Environmental Spheres

Lithosphere

Litho, Greek for “stone”

Atmosphere

atmo, Greek for “air”

Hydrosphere

hydro, Greek for “water”

Biosphere

bio, Greek for “life”

L

A H B Interacting

spheres

The Solar System

Figure 1-6: “Elliptical” orbits – Pluto is NO longer one of the planets in our

solar system as of 2006

“3rd Rock from the Sun” (93 million miles)

Size

Diameter – approx. 8,000 miles (12,800 km) at

the equator

5th largest in diameter

Size and Shape of Earth

Size and Shape of Earth

Earth’s highest pt: 29,000 ft

above sea level.

Lowest point: 36,000 ft below

sea level

More bulgy at the equator: a

difference of 0.3%.

As a result, it’s not a

‘true/perfect’ sphere (circle),

but an “Oblate Spheroid”,

slightly flat on top and bottom.

Size and Shape of Earth

Size and Shape of Earth

Angle of Tilt

See “imaginary rotation axis”.

Interesting fact about Earth:

The Earth tilts towards the east, at an angle of 23.5 degrees.

This is called the “inclination of the rotation axis”.

The Geographic Grid

The Combination of Latitude and Longitude Lines

Summary (Geographic Grid)

Longitude (also called Meridians) Measures distance east and west around the globe,

beginning at the Prime Meridian

Important longitude lines: Prime Meridian & International Date Line

0-180 degrees East or West

Latitude (also called Parallels) Location on the Earth’s surface between the equator and

the north or south pole

Important latitude line: Equator

0-90 degrees North or South

The Geographic Grid

The Equator (next slide) – the line thru the earth’s middle

Latitude (run north and south of Equator)

Longitude – E/W of the Prime/Greenwich Meridian

They are used to establish location, for navigation and for telling time.

The circle is 360 degrees around; therefore since there are 24 MAJOR longitude lines, each line is 15 degrees, same as ONE HOUR. So 360 degrees = 24 hours.

The Equator

More interesting facts

about Earth:

Earth ALWAYS points

to ‘Polaris’, the North

Star

Earth moves/ rotates

from West to East.

Great and Small Circles

A great circle is the largest circle than can be drawn on a sphere and they bisect the Earth into 2 equal halves e.g.

The Equator

The Prime Meridian

The Sun’s Circle of Illumination (see “Blue Beauty” NASA slides)

Small circles are any other circles that can be drawn.

Latitude: Parallels

There are 7

important parallels.

Measures from 0º to

90º N and S of the

equator.

Also, the “Tropics” or

tropical areas are

hotter, due to the

‘bulge’.

Longitude: Meridians

0 degrees Longitude passes thru

Greenwich, England. And it’s then

measured East and West

Measures from 0º to 180º E & W

of the Prime/Greenwich Meridian

Established in 1884 at the

International Meridian

Conference in Washington, D.C.

Also used for determining World

Time (every 15 degrees is an hr)

Regions on Earth

Regions on Earth (Latitude bands)

Low latitude » 0º – 30º N and S (close to Equator)

Mid latitude » 30º – 60º N and S

High latitude » 60º – 90º N and S (close to poles)

Equatorial » within a few degrees of the equator

Tropical » within the tropics between 23.5º N and 23.5º S

Subtropical » 25º – 30º N and S

Polar » within a few degrees of the North and South Pole

Earth Movements

Rotation on Axis (Daily)

One complete rotation is 24 hrs

Rotation Direction (West to East), see next slide

Rotation Speed, see table and pg 15-16

Revolution Around Sun (Annual)

365 days, 5hrs, 48 minutes and 46 seconds, simplified to 365.25 or 365 ¼ days

Leap Year

Rotation Direction

West to East

Rotation Speed

Note: Always

constant speed,

only DISTANCE

at each location

varies!

Annual March of Seasons

Solstices – Summer & Winter; unequal daylight (see

next slides)

Equinoxes – 12 equal hours of daylight; start of Spring

and Fall (anywhere between the 20th and the 23rd)

Also, see Table 1-7 (pg 22)

Solstices

Solstices

Equinoxes

Changes in Daylight

Time Zones

Accurate calendars have been kept by great civilizations for 1000s of years – the Egyptians, Mayas, Aztecs, Chinese, Indians, etc. Pg 23 (Babylon – 2,000 B.C.)

A.M. & P.M. are Latin words (pg 23). “Meri” (highest) is the root word for “Meritorious”.

3 units of natural time – the year, month and day. Everything else is man-made (hour, minute, second, etc)

Time Zones

Standard Time – starts at the Greenwich Meridian (GMT) or ‘Zulu’. Now called UTC (Universal Time Coordinated).

All areas to the east of the Prime Meridian are ‘ahead’ in time, and all areas to the west are ‘behind’ in time.

Some countries have one time zone, while others have several. Russia has 9.

International Date Line (further slides)

World Time Zones

U.S./Canada Time Zones

International Date Line

Starts at 180 degrees; this is also where a NEW DAY (new DATE) begins i.e. 12 Midnight.

It is the OPPOSITE of the Prime Meridian (zero degrees longitude) in Greenwich i.e. 12 Noon

There is a difference of 12 hours between the Prime Meridian (zero degrees) and the International Date Line (180 degrees longitude)