01:Seasons, Day vs. Night, Earth in SpaceWorld Climate PatternsWorld Geo 3200/3202Unit 2November 2010

Outcomes• 2.1.1 Distinguish between the terms rotation

and revolution. (k)

• 2.1.2 Explain how cloud cover influences the range of temperatures from day to night. (k)

• 2.1.3 Define the terms equinox and solstice. (k)

Outcomes• 2.1.4 Explain how changes in the seasons, in the

northern hemisphere & southern hemisphere, relate to the earth’s revolution around the sun. (k)

• 2.1.5 Describe the factors that account for differences in length of day as seasons change. (k)

• 2.1.6 Describe the factors that account for differences in temperature as seasons change. (k)

Rotating vs. Revolving (notes)• The earth rotates (spins) on its axis which

takes 24 hours and results in day and night.

• The earth revolves (orbits) around the sun which takes 365 days and results in seasons.

• For example, the use of the term revolves is correct in this sentence. "The moon revolves around the earth.“

Day & Night• It is the earth's rotation on its axis that results

in night and day.

• As Newfoundland rotates away from the sun it appears that the sun is setting in the west. In actual fact you are rotating away from the sun to the east.

• In the morning it appears that the sun rises in the east. In actual fact you are rotating towards the sun from the west.

Temps & Cloud Cover

•Nightly cloud cover reduces the range of temperature from day to night. ▫Clouds reflect heat waves; ▫heat below clouds is reflected back to

earth; ▫without clouds heat escapes giving colder

nights.

Temps & Cloud Cover• Lack of cloud cover

contributes to temperature patterns in the desert. –Lack of cloud cover in

the day results in high daily temperatures; –however in the night the

lack of cloud cover allows the heat to escape resulting in cold nightly temperatures.

Differences in Day Length• The tilt of the earth’s axis combined with

the earth’s rotation in orbit around the sun results in different day lengths.

• In June, because of the tilt on the earth's axis, the north pole points towards the sun and receives more hours of exposure to the sun hence giving it longer days.

• You can see that as the earth rotates Newfoundland "N" will spend more than 1/2 the time in sunlight. Light until 9:30 PM sunrise at 5:30 AM

Differences in Day Length• In December, because of the tilt on

the earth's axis, the north pole points away from the sun and receives fewer hours of exposure to the sun hence giving it shorter days.

• You can see that as the earth rotates Newfoundland "N" will spend less than 1/2 the time in sunlight.

• Here the northern hem. rotates out of the sun for long periods. Dark at 5:30 PM, sunrise at 8:00 AM

The Earth-Sun Relationship•http://www.youtube.com/watch?v=DuiQv

PLWziQ•Review Questions 1

SEASONS•The tilt on the earth's axis & the revolution

of the earth around the sun

•These two features of the earth-sun relationship mean that different latitudes on earth receive different directness of light at different times.

•When the sun hits more directly the latitude gets hotter temperatures and what they call summer.

Equinox and Solstice•Solstice:

▫sun is directly over head @ 12 noon on 23.5º North or South;

▫occurs Dec 21 & June 21; ▫longest day of the year & shortest day of the

year. •Equinox:

▫sun is directly over head @ 12 noon on the equator;

▫occurs Sept. 21 & March 21; ▫equal length of night and day everywhere on

earth

Tropics vs. The Poles• The term tropics fosters

images of warm climates.

• In everyday language it refers to warm equatorial climates.

• The tropics are located between 23.5 degrees north and 23.5 degrees south.

The Tropics

Tropics vs. The Poles

•This is important because the more direct the sunlight the more intense the heat.

•The further you move outside the tropics the more severe the seasons.

•The length of day varies more the further you move from the equator.

Tropics vs. The Poles

•When light hits the earth towards the poles it is on a severe angle which decreases the intensity of heat.

•The same light/heat energy is spread over a greater area

•Fig 4.3 “Solar Intensity & Latitude” in your text

Latitude

• Copy Fig 11-3. The Effects of latitude on Climate

• Using the diagram as a guide, explain why areas far from the equator experience colder temperatures than places near the equator

Summer & Winter Temperatures•There are two reasons for the difference

in temperature during these seasons:

▫more direct sunlight gives greater intensity of heat

▫longer summer daylight hours means there are more heating hours and fewer cooling hours

•Review questions 2