Seasons (cont'd)

The Earth is "tilted"

This image shows the tilt of the Earth's axis of rotation. During the summer in the Northern Hemisphere, the most direct sunlight strikes well north of the equator. On June 21 of each year the sun shines directly downward on the Tropic Of Cancer. The Tropic of Cancer is an imaginary line that runs parallel to the equator at 23.5 degrees north latitude.

During the Northern Hemisphere winter a similar situation occurs, however the most direct sunlight strikes well south of the equator. On December 21 of each year the sun shines directly downward on the Tropic of Capricorn. The Tropic of Capricorn is an imaginary line that runs parallel to the equator at 23.5 degrees south latitude. This abundance of direct sunshine in the Southern Hemisphere is why Adelaide, Australia is hot in January.

"White Nights"
As mentioned earlier there are locations in the world in which the sun stays up for 6 months in a row and then the sun does not come up for the following 6 months. The only two places on earth to find 6 straight months of dark or day are the North Pole and the South Pole. Locations north of 66.5 degrees north latitude have at least 1 day during which the sun does not set each year. Locations south of 66.5 degrees south latitude can also claim at least 1 day without a sunset per year.

Look at the image above of the Northern Hemisphere summer and try to explain why the sun does not go down at the North Pole for so long.