1. Seasons
Seasons are periods of time over the course of a year during which certain weather conditions prevail.
Climate describes the average weather conditions over a long period of time at a particular location.
Until the 1500s, people living on Earth did not understand why there were seasons.
In this presentation you will explore the reasons why we have seasons.
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2. Why Are There Seasons? The main reasons why seasons occur are:
23.5°
the Earth’s surface is curved
the Earth orbits the Sun
the Earth rotates
the Earth is tilted on its axis
It is because of these reasons that not all of the places on Earth receive the same amount of light and heat energy from the Sun everyday throughout the year.
As a result, some places on Earth have four seasons; four marked periods where the prevailing weather conditions and temperatures are different to each other. These seasons are spring, summer, fall and winter.
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3. The Earth’s Orbit of the Sun
The Earth takes approximately 365 days to complete an orbit of the Sun.
December
June
September
March
Earth’s orbit N S
The combination of the Earth’s spin, tilted axis, and movement around the Sun means the Northern and Southern Hemispheres are more directly exposed to the rays of the Sun at different times of the year. This causes the seasons in the two hemispheres to be opposite.
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4. Question 1
The Northern and Southern Hemispheres are more directly exposed to the Sun’s rays at different times of the year. This is due to the combination of the Earth’s spin, tilted axis, and orbit of the Sun.
Does this cause the opposite seasons in the two hemispheres?
Answer Yes or No.

5. Opposite Seasons
When a hemisphere is tilted toward the Sun the hours of daylight per day are greater than the hours of darkness. The hemisphere is in the season of summer.
However, the opposite hemisphere is tilted away from the Sun. The hours of darkness per day are greater than the hours of daylight. This hemisphere is in the season of winter.
The seasons of spring and fall are also opposite in the two hemispheres.
Near the equator, the hours of daylight are not affected by the tilt of the Earth as much. The hours of daylight are not so different throughout the year and the seasons are not so marked as a result.
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6. Question 2
When a hemisphere is tilted toward the Sun it is experiencing...
A) ... winter.
B) ... summer.

7. Climatic Zones
Different regions of the surface of the Earth experience different climates.
The divisions of the Earth’s surface according to prevailing climate and latitude are called climatic zones.
Climatic zones cover five areas of the Earth. They correspond with the five major circles of latitude that are the:
Arctic Circle
Tropic of Cancer
Equator
Tropic of Capricorn
Antarctic Circle
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8. Climatic Zones
Temperate climates lie between the tropic line and polar circle in each hemisphere. These are split into northern and southern zones.
The Arctic Circle is situated around the North Pole.
Equator
The Tropic of Cancer lies north of the equator and is also known as the Northern tropic.
The Antarctic Circle is situated around the South Pole.
The Tropic of Capricorn lies south of the equator and is also known as the Southern tropic.
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9. Polar Climatic Zones
The polar climatic zones are the parts of the Earth’s surface forming a cap over a pole where we find extreme cold temperatures. These areas are found above the Arctic Circle and below the Antarctic Circle.
During their respective summer seasons, these areas experience 24 hours of daylight per day.
During their respective winter seasons, these areas experience 24 hours of darkness per day.
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10. Temperate Climatic Zones
The temperate climatic zones are the parts of the Earth's surface that lie between the Arctic Circle and the Tropic of Cancer and between the Antarctic Circle and the Tropic of Capricorn. These areas are characterized by a temperate climate.
These areas experience spring, summer, fall and winter.
When one zone is experiencing one season, the other zone is experiencing the opposite season.
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11. Tropical Climatic Zones
The tropical parts of the Earth's surface lie between the Tropic of Cancer and the Tropic of Capricorn. This area is characterized by a hot climate.
The number of daylight hours does not change much throughout the year, so the temperature is mainly very warm.
These areas do not experience four seasons, instead they have wet and dry seasons.
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12. Question 3
Which of the following climate zones experiences wet and dry seasons?
A) Polar
B) Temperate
C) Tropical
D) All of these

13. Sunlight and Seasons
In spring the hemisphere begins to receive more daylight each day. This, together with the temperature starting to rise, causes the plants to begin to grow.
Summer has days with the most hours of daylight, and the warmest temperatures. It is also the season when most fruit, vegetable, and other plants are in flower.
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14. Sunlight and Seasons
During the fall, the hours of daylight each day become less, and the temperature cools. Some plants lose their leaves.
Winter has days with the least hours of daylight, and the lowest temperatures. In some areas winter brings ice, snow and bad weather.
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15. Question 4
"In some places on Earth, the hours of daylight per day vary throughout the year." Is this statement true or false?
Answer True or False.

16. Solstices
A solstice marks the two days of the year that have the least and the most hours of daylight. The solstices occur in June and December.
Tropic of Capricorn
Tropic of Cancer
The solstices in the Northern and Southern Hemisphere are opposite; the summer solstice of one hemisphere is the winter solstice of the other.
During the June solstice the Sun is over the tropic of Cancer. It is the day with the most daylight hours in the Northern Hemisphere and the least daylight hours in the Southern Hemisphere.
During the December solstice the Sun is over the tropic of Capricorn. It is the day with the most daylight hours in the Southern Hemisphere and the least daylight hours in the Northern Hemisphere.
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17. Equinoxes
An equinox marks the time when every place on Earth has 12 hours of daylight and 12 hours of darkness.
Equinox
March 21st
An equinox happens twice a year, during March and September.
The spring equinox in the Northern Hemisphere will be the fall equinox in the Southern Hemisphere, and vice versa.
September 22nd
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18. Summary After completing this presentation you should be able to:
show knowledge and understanding of how seasons are related to the relationship of the Earth and the Sun
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