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Author Topic: Does the sun in winter heat everything the same?  (Read 2078 times)

Joshua

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Does the sun in winter heat everything the same?
« on: 24/10/2011 00:30:02 »
Joshua asked the Naked Scientists:
   
Does the sun in winter heat everything the same?

What do you think?
« Last Edit: 24/10/2011 00:30:02 by _system »


 

Offline Geezer

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Does the sun in winter heat everything the same?
« Reply #1 on: 24/10/2011 02:42:38 »
Hi Joshua,

Can you give us a bit more information? Do you mean "the same" as in Summer, or were you thinking of something else?
 

Offline Soul Surfer

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Does the sun in winter heat everything the same?
« Reply #2 on: 24/10/2011 09:02:12 »
Yes the sun's radiation on a sheet placed exactly perpendicular to it is essentially the same in winter and summer.  In fact it is slightly greater because we are nearest to the sun in our elliptical orbit in January.  The difference between winter and summer is due to the fact that the sun is lower in the sky (in the UK and other similar spots on the northern hemisphere) and so the same energy is spread over a larger footprint.  and also that the days are shorter and the nights longer (while we are looking at the cold of outer space).

One interesting aside is that the strength of the sun on your face while you are standing up is greater in winter.
 

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Does the sun in winter heat everything the same?
« Reply #3 on: 24/10/2011 09:30:13 »
Yes the sun's radiation on a sheet placed exactly perpendicular to it is essentially the same in winter and summer.  In fact it is slightly greater because we are nearest to the sun in our elliptical orbit in January.  The difference between winter and summer is due to the fact that the sun is lower in the sky (in the UK and other similar spots on the northern hemisphere) and so the same energy is spread over a larger footprint.  and also that the days are shorter and the nights longer (while we are looking at the cold of outer space).

One interesting aside is that the strength of the sun on your face while you are standing up is greater in winter.

Only if you ignore the fact that the Sun's radiated energy has been greatly attenuated because of the much greater distance it has to travel through the Earth's atmosphere before it reaches you.
 

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Does the sun in winter heat everything the same?
« Reply #4 on: 24/10/2011 18:28:52 »
True atmospheric attenuation does have a significant effect  I had forgotten to include that.  Checking it out, it could be around 40% difference between midday midsummer and midwinter at UK latitudes I reckon.
 

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Does the sun in winter heat everything the same?
« Reply #5 on: 25/10/2011 08:14:28 »
True atmospheric attenuation does have a significant effect  I had forgotten to include that.  Checking it out, it could be around 40% difference between midday midsummer and midwinter at UK latitudes I reckon.

It's difficult to ignore the effect if you live in Scotland. If you are lucky enough to actually see the Sun in January, it looks like a dull red disc in the sky. 
 

Offline syhprum

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Does the sun in winter heat everything the same?
« Reply #6 on: 25/10/2011 10:44:22 »
Down here in the South East January tends to be a very sunny month in fact more road accidents are caused by people being dazzled than are caused by snow.
 

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Does the sun in winter heat everything the same?
« Reply #7 on: 26/10/2011 09:06:41 »
This dimming is probably caused by particles in the air.  If the air is properly clear the sun will only be affected by a fraction of a stellar magnitude between it highest point and its lowest point at midlands latitudes.
 

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Does the sun in winter heat everything the same?
« Reply #8 on: 26/10/2011 14:36:21 »
This dimming is probably caused by particles in the air.  If the air is properly clear the sun will only be affected by a fraction of a stellar magnitude between it highest point and its lowest point at midlands latitudes.

Yes, I would think particulates and humidity have a lot to do with it. What about CO2 though? The Sun's radiation has to travel through a lot more CO2 at low angles. Would that affect the IR received? (I think the question has more to do with heat than visible light.)
 

Offline Pmb

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Does the sun in winter heat everything the same?
« Reply #9 on: 26/10/2011 17:33:47 »
Joshua asked the Naked Scientists:
   
Does the sun in winter heat everything the same?

What do you think?
Yes. When it's summer in the Northern Hemisphere its winter in the Southern Hemisphere. This is caused by the Earth's tilt. Since part of the time the earth tilts to the sun and the solar flux from the sun heat up the Earth. Same in the winter. Sprng and Fall are in between these two extremes.
 

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Does the sun in winter heat everything the same?
« Reply #9 on: 26/10/2011 17:33:47 »

 

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