# What’s The Reason For The Seasons?

## Presentation on theme: "What’s The Reason For The Seasons?"— Presentation transcript:

What’s The Reason For The Seasons?
Equal amounts of daylight WINTER SEASON SPRING SEASON Longest amount of daylight Shortest amount of daylight FALL SEASON SUMMER SEASON Equal amounts of daylight

Want to see this in action?
4. Explain how the North Pole in the summer differs from the North Pole in the winter. Include mention of how this compares to the South Pole. In the Summer, the North Pole gets 24 hours of daylight. In the Winter, the North Pole has 24 hours of night/darkness. This is exactly opposite in the South Pole. Want to see this in action? Visit the 8th grade wiki and see the two time lapse videos of the sun traveling through the sky in Alaska in the summer & winter. What a difference!

5. In Ohio, describe how the sun appears to move in the sky during the summer as compared to the winter. & September 21 & September 21 The sun travels longer through our sky, reaching a higher arc as it moves, during the summer. This is because we are tilted towards the sun and results in a longer time facing it, so we have a longer amount of day light. During the winter, this is exactly the opposite. We have shorter days because we are tilted away from the sun. The sun makes a much lower arc across out winter-day sky. At the equinoxes, when we experience an equal amount of day and night, our sun travels in a “medium” sized arc across the sky, in between the two solstices. See the diagram here to show the path of the sun at each solstice and equinox.

5. In Ohio, describe how the sun appears to move in the sky during the summer as compared to the winter. The sun moves from the east horizon to the west horizon every day. Because it is in the sky longer during the summer, it must reach a higher arc than during the winter, when daylight is less.

6. Identify the similarities between fall and spring equinoxes.
Both the autumnal (fall) and vernal (spring) equinoxes have: The same amount of daylight & night time (12 hours of each). Similar temperature ranges. Neither the Northern nor the Southern Hemisphere receiving direct sunlight/ heat.

The length of daylight is gradually increasing.
7. Describe the length of daylight in the following situations: a. As the Northern Hemisphere moves from the Winter Solstice to the Vernal (Spring) Equinox. The length of daylight is gradually increasing.

The length of daylight is gradually increasing.
7. Describe the length of daylight in the following situations: b. As the Northern Hemisphere moves from the Vernal (Spring) Equinox to the Summer Solstice, what happens to the amount of daylight we experience? The length of daylight is gradually increasing.

The length of daylight is gradually decreasing.
7. Describe the length of daylight in the following situations: c. Once we have experienced the Summer Solstice in the Northern Hemisphere, what happens to the length of daylight in the Northern Hemisphere during the season of summer. The length of daylight is gradually decreasing.

The length of daylight is gradually decreasing.
7. Describe the length of daylight in the following situations: c. The Autumnal Equinox is a marker of exactly 12 hours of daylight and 12 hours of night everywhere on Earth. What happens to the amount of daylight in the Northern Hemisphere as we move towards the Winter Solstice? The length of daylight is gradually decreasing.

8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The amount of sunlight shining on the Earth as a whole. does not change!

The amount of daylight in Ohio.
8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The amount of daylight in Ohio. ✔ = Daylight is longest on the Summer Solstice and shortest on the Winter Solstice. The amount gradually changes as we move from one solstice to the next.

does not change! The tilt of Earth’s axis.
8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The tilt of Earth’s axis. does not change!

does not change! The amount of daylight Earth experiences.
8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The amount of daylight Earth experiences. does not change!

8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The location of the sun’s direct rays of light. ✔ = The sun’s direct rays impact Earth causing summer. This happens in the Northern Hemisphere starting June 21; the Southern Hemisphere starts summer on December 21.

8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The amount of night in the Northern Hemisphere. ✔ = It is longest on the Winter Solstice and gradually decreases as we move towards the Summer Solstice. After the first day of summer, the amount of night gradually increases until it reaches its maximum amount again on the Winter Solstice.

does not change! The length of a calendar day.
8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The length of a calendar day. does not change!

The length of night the North Pole.
8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The length of night the North Pole. ✔ = On the Winter Solstice, the North Pole has 24 hours of night, but on the Summer Solstice it has 24 hours of daylight.

does not change! The length of a year.
8. Check as many of the following that change during one year; in the space to the right, explain how the ones you checked change during the year. The length of a year. does not change!

Did you know??? The summer solstice (June 21) has the longest amount of daytime of the year. Note: the day itself is still 24 hours long. It is also the beginning of summer. HUH? Even though it is the beginning of summer, we (in the north) haven’t hit our peak of warm temperatures… Right??

Did you know??? WHY??? The surface of our planet is approximately 75% water. Water takes longer to heat up than land. By June 21 the oceans are still cool from the winter time, and that delays the peak heat by about a month and a half. So… we consider that period from June through September (the fall equinox) to be our summer in the northern hemisphere.

The picture shows how the Sun moves through the sky for someone standing on the ground in Ohio during the summer solstice. The northern hemisphere is getting more direct sunlight, which heats the Earth most efficiently, than the southern hemisphere. This is summer for people in the northern hemisphere. During the summer, the Sun is also above the horizon longer than it is during the winter. The summer solstice marks the longest amount of daylight of the year.

The picture shows the view from the solar system of someone standing on the ground in Ohio during the winter solstice. The winter solstice, around December 21, occurs when the northern half of the Earth is tilted away from the Sun. Notice that the Sun is south of the equator. So, on the winter solstice, the northern hemisphere is getting less direct sunlight than the southern hemisphere. This day marks the longest amount of night of any day during the year in the Northern Hemisphere.

Did you know??? Winter officially begins on December 21, which is the shortest day of the year. Again… it is still 24 hours, but the amount of daytime is shortest on that day. How is it that we consider it the beginning of winter and not right in the middle? Again, think about the oceans…

Did you know??? In December, the water on earth still holds warmth from the summer, and the coldest days are still (on the average--not always! ) a month and a half ahead. We consider the period of time while the oceans “cool” to be winter. In the northern hemisphere, this means December - March (spring equinox).

The picture shows how the Sun moves through the sky for someone standing on the ground in Ohio during the winter solstice. During the winter, the Sun is also above the horizon for a shorter time than it is during the summer (the nights are long). The winter solstice contains the shortest amount of daylight of the year.

Notice how the tilt of the axis impacts the shadows on Earth
Notice how the tilt of the axis impacts the shadows on Earth. • Where the sun’s light is directly hitting (summer) Earth, the shadows are shortest. • Where indirect light hits Earth (winter), shadows are longest.

Did you notice the differences in shadow length
Northern Hemisphere Did you notice the differences in shadow length when you completed your lab?

Northern Hemisphere You should have seen that shadows are longer in the winter, when the sun is lowest in the sky. Shadows are shortest in the summer, when the sun is highest in the sky. During fall & spring, a shadow’s length is somewhere in between the two.

The picture shows the view from the solar system of someone standing on the ground in Ohio during an equinox. An equinox, around March 21 and September 21, occurs when neither half of the Earth points directly towards the Sun. In fact, the Sun is at the equator, so both halves of the Earth are getting about the same amount of sunlight.

Equinox literally means "equal night".
The picture shows how the Sun moves through the sky for someone standing on the ground in Ohio during an equinox. Equinox literally means "equal night". On the vernal (spring) and autumnal (fall) equinoxes, day and night are the same length. Neither hemisphere gets more sunlight than the other, so both have similar seasons (fall in one hemisphere and spring in the other).