The Seasons - PowerPoint Presentation

Slide1

The Seasons

We experience Seasons because the Earth does not receive the same amount of solar radiation at all times. When the Northern Hemisphere is tilted towards the Sun, we have Summer. The Sun’s rays hit the Tropic of Cancer directly.

The Tropic of Cancer is a line of latitude.Slide2

Winter

Notice here that the Sun’s rays are shining directly on the Tropic of Capricorn in winter. At this time the Northern Hemisphere is tilted away from the Sun….But the Southern Hemisphere is not. They are experiencing their summer .

The Tropic of Capricorn is another line of latitude. Slide3

What happens at the Poles?

An interesting phenomenon occurs at the North Pole in the winter. When the Northern Hemisphere is tilted away from the Sun, the North pole receive little or NO sunlight!Slide4

Does this happen at the South Pole?

This can happen at the South Pole, too! In June, while we have our summer, the South pole is tiled away from the Sun and receives little or NO sunlight.Slide5

Now let’s look at all our Seasons

The word “equinox” literally means equal night. During the Vernal and Autumnal Equinox, the Sun’s rays fall directly on the equator. We experience equal hours of darkness and sunlight.

Vernal means Spring.Autumnal means Fall.Slide6

But what happens in the Summer?

In the first slide we learned that the Sun’s rays fall directly on the Northern Hemisphere in the Summer. June 20th is called the Summer Solstice

. At that time we have the largest number of daylight hours and the shortest number of hours of darkness.Slide7

Looking at the Winter Solstice

The winter solstice occurs on December 21st. At this time, the Northern Hemisphere is tilted away from the Sun and it receives the fewest hours of daylight and the largest numbers of hours of darkness.Slide8

Putting it all together

The Earth rotates Counterclockwise around the Sun.Summer Solstice= June 21stAutumnal Equinox (Fall) =Sept 22

ndWinter Solstice= Dec 21Vernal Equinox (spring)= March 21stSlide9

Here is a Summary Simulation

When we put all these ideas together, we can also see that the Southern Hemisphere has Winter when we have Summer AND they have Summer when we have winter. This reversal of the seasons is due to the 23.5o tilt of Earth’s axis.

http://www.videojug.com/film/why-does-the-earth-have-seasonsSlide10

What happens during an ECLIPSE?

An eclipse means some celestial body is cast in shadow. A solar eclipse means the Sun is in a shadow. A Lunar eclipse means the

Moon is cast in a shadow.Slide11

A Solar Eclipse

In a Solar eclipse, the NEW Moon is between the Sun and Earth.

The area of TOTAL shadow is called the

Umbra

. Think of an “umbrella” that shades you from sun or rain.

The area that is partially eclipsed is called the penumbra. Slide12

A Lunar Eclipse

In a Lunar Eclipse, the FULL Moon is in Earth’s Shadow. The Earth is between the Moon and Sun.

Again, you can see the area of total shadow is the umbra and the penumbra is only partially eclipsed.Slide13

Solar and Lunar Eclipses

Lets’ take a look of these special cases of the Lunar phases where the Sun, Earth and Moon are aligned. The first one does not show the umbra or penumbra.

https://www.youtube.com/watch?v=rVE8PFYlwSMSlide14

Umbra and Penumbra

This simulation shows the umbra and penumbra formation. During a Lunar eclipse, the Moon often appears to be blood-red. In a solar eclipse, we can see the corona of the Sun (the outer edge of the Sun’s atmosphere).

http://www.vox.com/2015/4/3/8332781/lunar-eclipse-blood-moon-how-to-see