The Sun is the ultimate

source of energy for life

on earth

(Earth’s core is the source of energy

for the movement of tectonic plates)

The sun is 1 milliontimes bigger than theearth, but the earth only

gets 1 billionth of itenergy

The sun is 93 millionmiles away (about 8 light

minutes)

Of all of the radiation that reaches earth,

only a small amount reaches the surface:

Some is radiated back into space by clouds

Some is reflected by light colored surface (snow)

Enough remains to warm the earth and provide energy for nearly all of its life forms

The atmosphere also prevents heat from

escaping back into space too quickly(Greenhouse Effect)

The SunThe Sun

Earth’s Rotation and Revolution

Earth’s Rotation and Revolution

Rotation – earth spins on its axis and one complete rotation equals day and night (24 hrs)

Revolution – earth revolves around the sun and completes one revolution in 365 and one quarter days; leap year adds a day to the calendar every

4 years.

Planetary Factors that Influence the Distribution of Heat from the Sun

Planetary Factors that Influence the Distribution of Heat from the Sun

The earth spins on its axis so half faces

the sun while the other half faces away

The earth is round, thereforeequatorial regions receive

moredirect sunlight than polar

regions

The earth is tilted on its axis 23 and a half degrees so at different points

in its orbit around the sun, part of it receives more direct sunlight than the

other, this causes SEASONS

Solstices mark the periods of the earth’s orbit when one end is farthest away while the other end is closest (June 21 and December 21).

Equinoxes mark the periods when all areas of the earth are equidistant from the sun (March 21 and September 21).

Influence of LatitudeInfluence of LatitudeThe angle of the sun’s rays are most direct at the equator and least direct, more dispersed, at the poles causing more intense heating in the mid-

section (TROPICS) and more intense cold at the poles (ARCTIC).

Lines of Latitude enable the earth to be divided into zones that are very generally defined by CLIMATE

Tropical Zones – from equator north and south to latitudes 23 degrees (north – Tropic of Cancer; south – Tropic of Capricorn); most places here are hot year around.

Temperate Zones – from 23 degrees N/S to 66 degrees N/S; generally cooler with a wide variety of temperature fluctuation.

Polar Zones – from 66 degrees N/S to the poles; suns rays strike very indirectly over a broad area, therefore these areas are always cold, bitterly cold in winter.