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Author Topic: Are seasons related to distance from the Sun?  (Read 1175 times)

Offline thedoc

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Are seasons related to distance from the Sun?
« on: 23/08/2012 14:30:01 »
Niya asked the Naked Scientists:
   
In the southern hemisphere, Christmas falls in the hot season rather than the cold season, how does this show that seasons on Earth are not related to the distance Earth if from the Sun?

What do you think?
« Last Edit: 23/08/2012 14:30:01 by _system »


 

Offline CliffordK

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Re: Are seasons related to distance from the Sun?
« Reply #1 on: 23/08/2012 16:53:35 »
Earth's distance from the sun varies slightly, but not significantly.  For the Northern hemisphere, the Earth is actually closest to the sun in the winter, and farthest from the sun in the summer.

However, the seasons are primarily determined by the tilt of Earth's axis of about 23.4.  It remains at a fixed angle as the earth rotates around the sun once a year.
In the winter (for the North), the tilt is such that the southern hemisphere is tilted towards the sun, and the northern hemisphere is tilted away from the  sun.  Thus, the north gets less solar exposure, and the days are shorter.

In the summer (for the North), the tilt is such that the north is tilted towards the sun, and the south is tilted away from the sun.  Thus the North gets more solar exposure and the days are longer. 

In the spring and fall, the sun is to the side of the tilt, and thus generally over the equator.
 

Offline RD

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Offline CliffordK

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Re: Are seasons related to distance from the Sun?
« Reply #3 on: 24/08/2012 03:09:40 »
similar question ... http://www.thenakedscientists.com/forum/index.php?topic=43677
Excellent diagram.

Of course, the "long distance" vs "short distance" in the diagram is the distance that the sun rays travel through the atmosphere, and not as much the distance from the sun.

The sun varies between being directly over the tropic of cancer, 23.5N on the summer solstice (June 22 or 23), and directly over the tropic of capricorn, 23.5S on the winter solstice (December 21 or 22).  The solstices are the longest and shortest days of the year.

It is directly over the equator on the spring and fall equinoxes, March 20 & September 22/23.

Due to the curvature of the Earth, the poles will experience 24 hour daylight in the summer, and 24 hour darkness in the winter.  The closer one is to the poles, the longer the days in the summer and the shorter the days in the winter (keeping in mind that summers and winters are reversed in the North and South).
 

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Re: Are seasons related to distance from the Sun?
« Reply #3 on: 24/08/2012 03:09:40 »

 

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