Our amount of daylight hours depends on our latitude and how Earth orbits the sun. Earth’s axis of rotation is tilted from its orbital plane and always points in the same direction — toward the North Star. As a result, the orientation of Earth’s axis to the sun is always changing throughout the year as we revolve around the sun. Sometimes the axis points toward the sun and other times away from the sun. As this tilt changes throughout the year, so does the distribution of sunlight on Earth’s surface at any given latitude. This tilting leads to a variety of solar rays energy that changes with latitude. This causes a seasonal variation in the intensity of sunlight reaching the surface and the number of hours of daylight. The variation in intensity results because the angle at which the sun’s rays hit the Earth changes with time of year. This spinning of Earth like a top explains our daily cycle of night and day. The tilt of the Earth’s axis also defines the length of daylight. Daylight hours are shortest in each hemisphere’s winter. Between summer and winter solstice, the number of daylight hours decreases, and the rate of decrease is larger as you travel northward or southward. The fewer sunlight hours the colder the nights. How fast Earth spins determines the number of hours in a given day. As Earth orbits the sun it spins about its axis approximately once every 24 hours. But this is slowly changing with time. About 650 million years ago there were only about 22 hours in a day. If we flatten the earth on December 21st, the Northern Hemisphere's winter, observe the poles! The north pole is completely darkened and the south pole is completely light. The light makes a bell shape showing how the daylight hours are shorter near the north pole and the daylight hours are getting longer as you move toward the south pole. Flatten the earth out again when the northern hemisphere is in summer and you can see again that bell like shape that shows the longest days in the north and the shortest days in the southern hemisphere. This is how the Earth looks from the moon. The seasons, the daylight hours, the night time hours...all of this is due to our TILT, the ANGLE OF THE SUNS RAYS and the Earth's spin as it revolves around the Sun. To see the big picture you have to step back and really LOOK at the information you have been working with and let it sink into brain. There is no way you can understand the universe if you have your blinders on!!!
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Mrs. TaylorI love science! Everything about the world is interesting and never boring. I love to study plants, animals, insects, and people. My favorite subjects are my students who are the most unique organisms on the planet! Categories |